What Is SEO? The Complete Guide to On-Page, Off-Page, Technical, Local and AI SEO

Open Google today and search for “restaurants near me”, “website design cost” or “Phuket sea view hotel”. Every result on the first page belongs to a site that has, deliberately or not, done SEO. And the higher a result sits, the larger the share of clicks it tends to receive, while results near the bottom of page one get only a sliver. That gap is why SEO has become a skill every business needs to understand.

Many people still think SEO means “stuffing lots of keywords into articles” or “buying backlinks from other sites”. In reality, SEO has grown into a complete discipline combining content strategy, technical optimization, authority building, local presence and, most recently, AI SEO: preparing your site so ChatGPT, Perplexity, Claude, Gemini and Google AI Overview can use it as a source.

This guide covers everything you need, from the basic definition to the four pillars of SEO, ten on-page essentials, link building, Core Web Vitals and schema, local SEO, AI SEO, the tools professionals use, and how to judge whether investing in SEO makes sense for you.

At Southern Whale, our freelance team works on SEO for businesses across Southern Thailand and beyond, and every project starts with a correct understanding of the fundamentals. In this guide you’ll see why good SEO is one of the strongest long-term investments among marketing channels.

One note before we start: this is a long guide, but every section is practical, working knowledge rather than filler. Whether you’re a business owner, marketing manager, web developer or content creator, it’s meant to be a reference you can bookmark and come back to.

What is SEO? The definition that matters today

SEO stands for Search Engine Optimization: “optimizing a website so search engines understand it and rank it higher in search results.” The end goal is to make your site appear on the first page, ideally near the top, when people search for terms related to your business on Google, Bing or other search engines.

That technical definition doesn’t capture how SEO works today, though. Google’s own “Search Quality Rater Guidelines” put heavy emphasis on E-E-A-T (Experience, Expertise, Authoritativeness, Trustworthiness), which content creators need to demonstrate on every page, not just optimize for search terms.

From a business point of view, SEO is “an investment that lets customers find you on their own without paying for each click”. Every time someone searches Google and finds your site near the top, you get traffic without paying per click, and it’s highly qualified traffic, because these people have clear intent: they’re already looking for what you sell. That’s different from ads, which people sometimes click without meaning to.

SEO has also expanded into AI SEO, sometimes called GEO (Generative Engine Optimization): optimizing your site so ChatGPT, Perplexity, Claude, Gemini and Google AI Overview use it to answer questions in conversation, not just on the classic results page. It’s the biggest shift in SEO in a decade.

Why SEO matters for businesses in Thailand

Most people in Thailand are online, and Google remains the main search engine they use every day. That adds up to an enormous number of searches, a market your business can tap into through SEO.

What makes SEO more important than ever is changing user behavior. Many people trust organic results more than paid ads, and some scroll straight past ads to read the organic listings first. That makes SEO one of the best-returning channels.

Ad costs on Google Ads and Facebook Ads in Thailand also keep climbing, and some keywords in real estate, insurance and automotive are expensive per click. SEO, by contrast, keeps delivering long after the work is done, so its long-term cost per acquisition is often much lower than paid ads.

For businesses in the South, in Phuket, Krabi, Phang Nga and Surat Thani, SEO matters even more, because large numbers of tourists search Google before they travel. English searches like “best restaurant phuket”, “things to do krabi” or “phuket hotel near patong beach” attract international travelers who are actively planning. Ranking well for terms like these can bring a steady stream of direct enquiries and bookings.

Most importantly, SEO is a long-term asset that compounds. Ads stop the moment you stop paying. A site with strong SEO can stay visible for years, and the return on that work grows as time goes on.

The four pillars of SEO: on-page, off-page, technical, local

SEO can be divided into four pillars that need to be balanced. Neglect any one and ranking gets harder, because Google looks at your site holistically, not just one page at a time. Here’s what each pillar is and how it works.

1. On-page SEO means optimizing the page itself: title tag, meta description, headings (H1, H2, H3), URL, image alt text, internal links, content quality and keyword placement. You control all of this completely, and it’s the starting point of every SEO project.

2. Off-page SEO means building credibility through signals from other sites: backlinks, brand mentions, social signals, PR and co-citation. Google treats backlinks as a “vote of confidence”. Sites with high-quality backlinks from respected sites tend to rank higher.

3. Technical SEO means optimizing the engine behind your site: site speed, Core Web Vitals, mobile responsiveness, schema markup, XML sitemap, robots.txt, crawlability, indexability, HTTPS and structured data. See our SEO Audit service for more detail.

4. Local SEO means optimizing for local results: Google Business Profile (formerly Google My Business), local citations, reviews, NAP consistency (name, address, phone), local backlinks and geo-targeted content. It’s essential for businesses with a physical location that customers visit, such as restaurants, hotels, clinics and spas.

There’s also an emerging fifth pillar, AI SEO or GEO, which we cover separately below because there’s a lot to it and many practitioners are still getting to grips with it.

On-page SEO: 10 essential elements

On-page SEO is the first thing to get right on every page, because it’s the foundation Google uses to understand what a page is about and which searches it should rank for. Here are the ten elements to check on every page:

1. Title tag (around 50–60 characters). The headline shown in search results. Include your primary keyword, your brand name and a clear value proposition. Example: “Website Design in Phuket | Southern Whale”.

2. Meta description (around 150–160 characters). The description shown in search results. Write it to earn the click, not just to summarize the page. A compelling description can raise your click-through rate.

3. H1 tag (one per page). The main heading of the page. It should match search intent and include your primary keyword.

4. H2/H3 hierarchy. Break content into subheadings so it’s easy to scan. Google uses headings to understand the structure of an article. See our Rank Math Pro page for a plugin that helps with on-page optimization.

5. URL slug (short, with the keyword). For example /blog/what-is-seo/, not /blog/post-123. Short, descriptive, keyword-relevant.

6. Image alt text. Every image needs alt text that describes it, with a keyword where it fits naturally, not “image1.jpg”. This helps both accessibility and image search.

7. Internal linking. Link to other relevant pages on your own site within each article. It helps Google understand your site structure and passes authority to important pages.

8. Natural keyword use. Use your primary keyword where it fits naturally, along with synonyms and related terms. Don’t aim for a target “density”; Google is very good at spotting keyword stuffing.

9. Content depth and quality. Cover the topic thoroughly enough to fully satisfy the searcher. The right length depends on the query: some need a short, direct answer, others a comprehensive guide.

10. Schema markup. JSON-LD structured data that tells Google whether a page is an Article, Product, Review, FAQ, Recipe and so on. It can earn rich results in search, which help your listing stand out.

Beyond these ten, there are secondary factors such as Open Graph tags (for social sharing), canonical URLs (to prevent duplicate content) and hreflang (for multilingual sites). But the ten above are the most important to get right on every page. Our on-page SEO checklist goes into more detail.

Off-page SEO and link building that works

Off-page SEO is about building your site’s credibility in Google’s eyes through signals from other sites. The main factor is the backlink (a link from another site to yours), which has been one of Google’s most important ranking signals since the company was founded.

A good backlink has these qualities:

Comes from an authoritative site, as gauged by tools like Ahrefs or Moz
Relevance: the linking site is in a related field. A food site should get links from food or travel sites, not sports sites.
Followed: a link Google can follow (not marked nofollow)
Varied anchor text: not every link using the same anchor text, which looks manipulative
Natural placement: the link sits within content, not in a footer or sidebar
Diverse sources: links from many different domains are worth more than many links from a single domain

8 white-hat link-building methods:

Guest posting: write articles for respected sites in your field in exchange for an author bio link
Skyscraper technique: find top-ranking content for your target keyword, create something better, then ask sites linking to the old piece to link to yours
Journalist requests: answer reporters’ questions through source-request services to earn links from news sites
Broken link building: find broken links on authoritative sites and suggest your resource as a replacement
Resource page outreach: find resource pages listing sites in your niche and ask to be included
Digital PR: create original research, infographics or newsworthy content and pitch it to media outlets
Local citations: list your business in relevant directories (for Thailand, for example Wongnai, Yellow Pages, TripAdvisor)
Brand partnerships: partner with other brands in your niche to cross-promote and link

Backlinks to avoid (they risk a Google penalty):

Buying backlinks from gig marketplaces
Obvious PBNs (private blog networks)
Comment spam on blogs and forums
Large-scale link exchanges
Footer links from templates or themes

Google uses an AI-based system called SpamBrain to detect link manipulation. Unnatural backlinks are typically ignored (neither helping nor hurting), but in serious cases a site can receive a manual action that removes it from Google results altogether.

Technical SEO: Core Web Vitals and schema

Technical SEO is the engine that lets your site rank. Even with great content and great backlinks, if your technical SEO is broken, Google can’t rank you properly. Here’s what to cover:

1. Core Web Vitals (three metrics)

Google has used Core Web Vitals as a ranking signal since 2021. The three metrics are:

LCP (Largest Contentful Paint) ≤ 2.5 seconds: how long the largest piece of content takes to load
INP (Interaction to Next Paint) ≤ 200 ms: how quickly the page responds to interaction (it replaced FID in 2024)
CLS (Cumulative Layout Shift) ≤ 0.1: layout stability (no jumping around)

How to optimize: use a CDN such as Cloudflare, modern image formats (WebP, AVIF), lazy loading, code splitting and critical CSS. Many sites can pass Core Web Vitals with this toolkit without a full rebuild. See our Core Web Vitals guide.

2. Mobile responsiveness and mobile-first indexing

Google uses mobile-first indexing, meaning it primarily indexes the mobile version of your site. In Thailand most people browse on their phones, so a site that isn’t responsive will struggle to rank. Test your pages with Lighthouse or PageSpeed Insights.

3. Schema markup (JSON-LD)

Schema is structured data that tells Google what a page is. There are many types:

Article/BlogPosting: articles
Product + Offer + AggregateRating: products
LocalBusiness: local businesses
FAQPage: FAQ content
HowTo: step-by-step tutorials
Review: product or service reviews
BreadcrumbList: breadcrumb navigation
Recipe: food blogs
VideoObject: videos

Complete schema can earn rich results in search, such as star ratings, prices and stock status. These make your listing stand out and can raise click-through rates without any change in ranking. Our Schema Markup guide covers implementation.

4. XML sitemap and robots.txt

sitemap.xml tells Google which pages exist on your site (submit it in Google Search Console)
robots.txt tells crawlers which areas not to crawl (such as admin panels or staging environments)

5. HTTPS and SSL certificates

Every site should run on HTTPS. Chrome shows a “Not Secure” warning for sites still on HTTP. Free certificates are available from Let’s Encrypt or through Cloudflare.

6. Site architecture (crawlability)

Every important page should be reachable within about three clicks of the homepage
Use breadcrumb navigation
Avoid orphan pages (pages with no internal links pointing to them)
Keep URL structure clear (for example /category/subcategory/post)

7. Page speed optimization

Beyond Core Web Vitals, overall speed matters too. Aim for strong Lighthouse scores on every page and check them with PageSpeed Insights.

Local SEO for businesses in Phuket, Krabi and Phang Nga

If your business has a physical location, local SEO should be your first priority. Google shows the Local Pack (three results with a map) above the organic results when people search “near me” or include a place name. Getting into the Local Pack can bring a lot of high-intent visitors.

A 10-point local SEO checklist:

Google Business Profile (GBP): claim it free at business.google.com and fill in everything (address, phone, website, opening hours, plenty of photos, products and services, attributes)
NAP consistency: your name, address and phone number must match everywhere (website, GBP, Facebook, directories). Even small differences can confuse Google.
Local citations: list your business in every relevant directory, such as Wongnai, Yellow Pages, Foursquare, Yelp and TripAdvisor
Google reviews: ask customers for reviews and reply to all of them, positive and negative, promptly
Local backlinks: earn links from local sites such as tourism portals, local business associations and provincial chambers of commerce
Geo-targeted content: write content that mentions your province, district and nearby landmarks, for example “restaurants near Patong Beach” or “spas in Phuket Old Town”
LocalBusiness schema: add JSON-LD with your name, address, opening hours and service area
Google Maps embed: embed a map on your contact page
Local keywords in titles and H1s: include the province or district on relevant pages, for example “Hair Salon in Phuket Town”
Excellent mobile experience: most local searches happen on phones, often by people ready to visit soon

For businesses in the South, a big opportunity is English-language local SEO aimed at international tourists. Searches like “best phuket restaurant”, “krabi tour” or “phuket spa” are commercially valuable, and doing local SEO well for them can bring in a steady flow of visitors without paying per click. See our Local SEO service.

AI SEO: preparing your site for ChatGPT, Perplexity and AI Overview

This is the biggest trend in SEO right now. AI SEO, or GEO (Generative Engine Optimization), means optimizing your site so large language models use its information to answer users’ questions in conversation.

What’s happening? Gartner predicted that traditional search engine volume would fall by around 25% by 2026 as people turn to AI assistants such as ChatGPT, Perplexity, Claude, Gemini and Copilot. If your site doesn’t appear in AI responses, you’re missing out on the fastest-growing share of discovery.

10 AI SEO techniques that work:

llms.txt and llms-full.txt: create files at your domain root that tell AI crawlers what to collect (following the llmstxt.org proposal)
Allow AI crawlers in robots.txt: let in GPTBot, ClaudeBot, PerplexityBot, Google-Extended and others you’re happy to be read by
Q&A-format content: write in a question-and-answer style. AI likes this format because it maps directly to user queries.
Definitive statements: write “X is Y”, not “X might be Y”. AI pulls clear factual claims to cite.
Citations and sources: cite a source every time you quote a statistic. AI favors content with citations because it’s more trustworthy.
Complete structured data: FAQ, HowTo and Article schema with author and publisher, to help AI parse your content
Unique original research: AI likes first-party data that isn’t available anywhere else, such as findings from your own surveys
Authoritative author bios: show who the expert behind the content is, which supports E-E-A-T
Recent update dates: AI favors fresh content. Review older articles regularly and show a “last updated” date.
Direct answer box: open with a short summary that answers the question directly, which AI can use immediately

New tools track AI mentions, such as Brand Radar (Ahrefs), Profound and AthenaHQ, so you can measure how often your brand is mentioned in ChatGPT, Perplexity and Gemini results. For a deeper dive, read our guides to AI SEO, GEO and AEO.

5 SEO tools professionals rely on

There are hundreds of SEO tools on the market, but most professionals rely on these five:

1. Ahrefs: excellent for backlink analysis, keyword research and site audits, with one of the largest link databases on the market, plus Brand Radar for AI visibility

2. Semrush: an all-in-one platform covering SEO, paid ads and social, strong on position tracking

3. Google Search Console (free): the tool everyone must use. It shows impressions, clicks, positions, indexing status and Core Web Vitals straight from Google.

4. Google Analytics 4 (free): tracks behavior, showing user journeys, conversions and top pages

5. Rank Math Pro or Yoast SEO (for WordPress): on-page SEO plugins that guide optimization of every article. See our Rank Math Pro page.

Popular supporting tools:

Screaming Frog: site crawler for technical SEO audits
PageSpeed Insights (free): Core Web Vitals checker
Lighthouse (free, in Chrome DevTools): full page audit
Ubersuggest: a lighter-weight option for small businesses
Surfer SEO: content optimization using NLP

For a business just starting out: Google Search Console + GA4 + Rank Math covers most everyday SEO work.

How to judge whether SEO is worth it

This is one of the most common questions we hear. SEO pricing varies enormously across the market, from individual freelancers to large firms, so rather than quoting numbers, here’s what actually determines whether SEO pays off for you.

What drives the scope (and therefore the cost) of SEO work:

How competitive your market is: a niche local service needs far less work than a national e-commerce category
The state of your site: a technically sound site needs less fixing than one with speed, structure or indexing problems
How much content is needed: the number and depth of articles and landing pages
Link building: whether ongoing outreach and digital PR are included
Languages and markets: multilingual or multi-country SEO adds work
Reporting and strategy: how often you get reports and strategic reviews

Questions to ask any SEO provider:

Do they explain what they’ll actually do each month?
Do they cover technical SEO and link building, or only content?
Do they use white-hat methods only?
Do they report with real data from Search Console and Analytics?
Do they promise guaranteed rankings? (If so, be wary: nobody controls Google’s rankings.)

A simple way to estimate break-even:

Monthly SEO cost ÷ average order value ÷ conversion rate
= the number of visitors per month you need to break even

Plug in your own numbers. If the visitor count you need is realistic for your keywords, SEO is likely to be a sound investment.

If you’re considering outside help, see our SEO service. SEO typically starts showing results within a few months, depending on competition and your site’s starting point. We don’t guarantee rankings, but we’ll always do our best.

7 common SEO mistakes

Working with many different sites, we see the same mistakes again and again. Here’s what to watch out for:

1. Expecting results in one or two months SEO is a long-term investment. Meaningful results usually take several months, and the full effect builds over a year or more. If you expect results in a month or two, you’ll be disappointed. The fix: run Google Ads alongside SEO early on to generate revenue while SEO builds.

2. Keyword stuffing Repeating “Phuket website design, Phuket website design, Phuket website design” in every paragraph invites a penalty. The fix: write naturally, using synonyms and related terms.

3. Ignoring technical SEO Focusing only on content while neglecting Core Web Vitals, schema and mobile means you won’t rank. The fix: run an SEO audit regularly.

4. Buying cheap backlinks Cheap backlinks from marketplaces usually come from PBNs or spam sites and risk a penalty. The fix: stick to white-hat link building only.

5. Not tracking results Doing SEO without checking Google Search Console and GA4 means you don’t know what’s working. The fix: set up a dashboard and review your metrics regularly.

6. Copying content from elsewhere Duplicate content won’t rank. The fix: write original content, or use AI to help draft and then rewrite it thoroughly with your own insight.

7. Never updating old content An article that has sat on page one for three years will gradually slip. The fix: refresh older content on a regular cycle. Google values freshness for many topics.

Frequently asked questions

Q1: How long does SEO take to show results?

Typically, early movement appears within the first few months as new content gets indexed and starts ranking in middling positions, then gradually climbs. Clearer results usually take six months or more, with the strongest results building over a year or longer. New sites with no authority often take longer, while established sites with some SEO history tend to move faster. The main factors are competition in your niche, content quality, link building and technical health.

Q2: Can I do SEO myself, or should I hire someone?

You can do it yourself if you have time each week and are willing to spend a few months learning before you see results. You’ll need to be comfortable writing content, working with basic HTML/CSS and a CMS like WordPress, using tools like Ahrefs or Semrush, and reading Google Search Console. If you’re a busy business owner, hiring help is often more efficient, because an experienced provider already has the process, tools and experience.

Q3: SEO or Google Ads: which should I choose?

Both, ideally; it isn’t either-or. Google Ads is good for short-term traffic (when you’re launching a business or a new product), while SEO builds a long-term asset. A common approach is to lean on ads early while SEO matures, then shift more budget into SEO as it starts delivering. For keywords with very expensive clicks, SEO often offers much better long-term value.

Q4: How is AI SEO different from traditional SEO?

Traditional SEO optimizes your site to rank on Google’s results page. AI SEO optimizes your site so ChatGPT, Perplexity, Claude, Gemini and AI Overview use it as a source in their responses. What they share: quality content, structured data and authority. Where they differ: AI SEO emphasizes Q&A format, citations, llms.txt and allowing AI crawlers, while traditional SEO focuses more on rankings, backlinks and on-page tags. You need both, because people now search across Google and AI tools.

Q5: Where should a new website start with SEO?

Five steps: 1) keyword research to find the core terms for your business; 2) a technical SEO audit so your site passes Core Web Vitals and has schema and a solid mobile experience; 3) set up Google Search Console, GA4 and Bing Webmaster Tools; 4) write your cornerstone content, the core articles covering every key topic in your niche; 5) build local citations and brand mentions. Follow these in your first 90 days and you’ll have a solid foundation to grow from.

Q6: Can I use AI to write articles? Will Google penalize it?

Yes, you can. Google stated clearly in 2023 that it rewards helpful content regardless of how it’s produced, rather than penalizing AI content as such. But watch three things: 1) never publish a raw AI draft; edit it and add your own insight; 2) never use AI to churn out content at scale with no value; 3) make sure author information and E-E-A-T are clear. Used well, AI can speed up drafting without hurting quality.

Q7: My rankings dropped after a Google update. What should I do?

Follow four steps: 1) check the Google Search Status Dashboard to see what the update targeted (helpful content, spam, core update and so on); 2) use Google Search Console to identify which pages dropped; 3) read the latest Search Quality Rater Guidelines to understand what Google emphasizes; 4) improve the affected content in line with E-E-A-T (author bios, source citations, original insight, updated dates). Recovery often takes until a later update, and if it doesn’t come back, the content may need a fuller rewrite.

Q8: How is Thai-language SEO different from English SEO?

There are five main differences: 1) competition: English SEO is far more competitive because the market is global; 2) search volume: English keywords usually have much higher volume; 3) tool support: SEO tools have more limited data for Thai, so some keywords need manual analysis; 4) word segmentation: Thai is written without spaces between words and Google segments it with machine learning, so keyword variations need care; 5) local SERP features: Google Thailand’s Local Pack, Knowledge Graph and AI Overview can behave a little differently from the US. For businesses selling within Thailand, focus on Thai SEO first and add English as you scale, unless your customers are international tourists, in which case English matters from day one.

Summary and next steps

SEO today is no longer about stuffing keywords. It’s a complete discipline that blends four pillars (on-page, off-page, technical, local) with a fast-growing fifth: AI SEO. Sites that do all five well build a durable source of traffic that few other marketing channels can match over the long term.

For businesses in Thailand, especially in the South, in Phuket, Krabi, Phang Nga and Surat Thani, the opportunity is still wide open, because many competitors aren’t doing SEO thoroughly. Committing seriously to SEO over the long term gives you the best chance of becoming a go-to name in your field.

Your next steps:

If you haven’t started SEO yet: begin with the five basics: keyword research → technical audit → Google Search Console setup → cornerstone content → local citations
If you’re already doing SEO: check that all four pillars are covered, and start preparing for AI SEO (llms.txt, allowing AI crawlers, Q&A-format content)
If you’d like an expert to handle it: our freelance team at Southern Whale provides end-to-end SEO for businesses of every size