SEO Basics
SEO stands for search engine optimisation. It is the practice of making a website more visible in search results, so people can find it without you paying for each visit.
What is SEO?
When someone searches on Google, the engine decides which pages to show and in what order. Google says its systems look at “many factors and signals, including the words of your query, relevance and usability of pages, expertise of sources and your location and settings”.1 Links between pages are among them: Google uses them to “determine what pages are about and which might be most helpful in response to a query”.2 SEO is the discipline of understanding those signals and improving them.
The goal is to earn unpaid, or organic, positions in search results. Organic results sit below any paid adverts and get the majority of clicks. Unlike paid search, where visibility stops the moment a campaign ends, organic rankings built through SEO continue to drive traffic as long as the content stays relevant.
What SEO is not
SEO is not about tricking search engines. The tactics that gamed early algorithms have been closed off over time. What remains is more straightforward: create useful content, ensure the site is technically sound, and build a reputation worth citing.
It is also not a one-time fix. Search engines update their algorithms regularly, competitors improve their own sites, and what people search for shifts over time. SEO is an ongoing activity.
The golden rule of SEO
Create content for people, not algorithms. There is no SEO change worth making if it harms the user experience. A useful test for any SEO decision: if search engines didn't exist, would you still do it, and would it still benefit the user?
What are the four types of SEO?
SEO splits into four main disciplines:
- On-page SEO covers the content and signals on each page: title tags, headings, the depth and accuracy of the writing, internal links, and structured data.
- Technical SEO covers the infrastructure of the site: how quickly pages load, whether search engines can crawl and index everything, mobile usability, and site architecture.
- Off-page SEO covers what the rest of the internet says about the site, primarily through links from other websites, which act as votes of confidence.
- Local SEO covers visibility for businesses that serve a specific geography, including Google Business Profile, local pack rankings, and citations.
Two more sit alongside these. Ecommerce SEO applies the same four disciplines at catalogue scale, where faceted navigation, product variants and feed consistency create failure modes no editorial site has. And a newer area has emerged: optimising for AI-powered answer engines. AI search retrieves and cites content rather than ranking it, and Google’s own position is that “optimizing for generative AI search is optimizing for the search experience, and thus still SEO”.3 Google’s search ecosystem, spanning organic results, AI Overviews, AI Mode, Discover, News, Shopping, Maps and Lens, means understanding which types of SEO apply to each surface is worth establishing early.
Core SEO topics
New to SEO? Start with How to learn SEO, a structured path that sequences these topics in the order they build on each other. The topics below group into five areas: the foundations, how Google ranks and updates, the engines and surfaces where results appear, the white-hat and black-hat spectrum, and the practical starting points.
Foundations
- How search engines work. The crawling, indexing and ranking stages that decide whether a page can appear in results, and where.
- What is organic search?. The difference between paid and unpaid results, and why organic positions have lasting value beyond individual campaigns.
- Types of SEO explained. How on-page, technical, off-page and local SEO fit together as a discipline, and where ecommerce and AI search sit alongside them.
- Semantic search. How search engines interpret meaning and context rather than matching keywords literally.
How Google ranks and updates
- How does the Google algorithm work?. The core ranking signals Google uses to evaluate relevance, quality, and authority.
- What are Google core updates?. What core updates change, how often they occur, and what to do if rankings drop after one.
- Google algorithm updates. The taxonomy of core updates, spam updates, and the Helpful Content system: what each targets, how to identify which type affected your site, and the correct response for each.
- Does Google use clicks to rank?. What the antitrust disclosures and the 2024 leak actually show about click data in ranking, and why no universal CTR benchmark exists.
- Search personalisation. Why the same query returns different results for different people, how much Google’s newer personalisation features reorder results, and why non-determinism alone produces large variation on AI surfaces.
Engines and surfaces
- Google’s search ecosystem. The full range of Google surfaces (organic, AI Overviews, AI Mode, Discover, News, Shopping, Maps and Lens) and how each differs.
- Bing and the Microsoft search ecosystem. How Bing differs from Google, and what visibility on Copilot and ChatGPT Search requires.
- Bing ranking factors. How Bing’s ranking signals differ from Google’s, chiefly the user-engagement signals Microsoft states plainly (the often-repeated social-signals claim is not in its current documentation), and what to adjust for visibility across Bing, Copilot, and ChatGPT Search.
White hat, black hat, and risks
- White-hat SEO. The principles that align with search engine guidelines and build sustainable rankings.
- Black-hat SEO. The tactics that violate search engine guidelines and the ranking penalties they risk.
- Parasite SEO. Publishing on a high-authority third-party domain to borrow its ranking signals, and what Google’s site reputation policy does about it now that its manual actions no longer affect what searchers inside the EEA see.
- Negative SEO. The deliberate attempt to harm a competitor’s rankings: which attack vectors still work, and how to defend against them.
Practical foundations
- How long does SEO take?. Realistic timelines for ranking movement, and the factors that accelerate or delay results.
- SEO auditing. A systematic approach to identifying the technical, content, and off-page issues limiting a site’s visibility.
- Choosing a domain name. How domain choice affects brand recognition, trust signals, and long-term SEO.
- Common SEO myths. Eighteen persistent myths with a plain correction for each, from the Google Sandbox to keyword density, plus the newer set forming around AI search.
