SEO is the practice of improving a website’s visibility in the organic results of search engines. This guide explains how it works, its four pillars, what has changed with artificial intelligence and how to measure what really matters, with data and verifiable sources.
The essentials in 30 seconds
- SEO is about making a website findable, understandable and trustworthy for search engines, so that it appears in the organic (unpaid) results.
- Organic search drives roughly half of all website traffic, far more than paid advertising.4
- It rests on four pillars: technical, on-page, content and off-page. None of them works in isolation.
- AI is changing the results page: today, most searches on Google end without a click.2 Useful, trustworthy content remains the best defence.
What SEO is
SEO (Search Engine Optimization) is the set of techniques and best practices that make a website more understandable and relevant to search engines, with the goal of appearing in higher positions within the organic results, that is, the unpaid results.
Unlike paid advertising, organic traffic has no direct cost per click. It is the result of ongoing work on technical quality, useful content and reputation. It is a medium to long-term investment: results take time to consolidate, but they tend to be more stable and sustainable over time.
SEO seeks to answer three questions that a search engine asks about every page: can it find it, can it understand it and does it have reasons to trust it more than the alternatives?
Why SEO matters
Search remains the main starting point for finding information, products and services online. Several market studies estimate that organic search accounts for around 53% of website traffic, compared with about 15% from paid search4, although these figures vary by sector and by year.
Within the results, position makes an enormous difference. Backlinko’s analysis of millions of results indicates that the first organic result captures around 27.6% of clicks and that the top three combined gather more than half of all clicks.3 The second page is, in practice, rarely visited territory.
How search engines work
To understand SEO, you need to understand what happens behind the scenes. A search engine like Google works, in simplified terms, in three stages:1
- Crawling: automated robots (at Google, Googlebot) move across the web following links and downloading the content of the pages they find.
- Indexing: the crawled content is analysed, interpreted and stored in a vast index, organised by topics, words and quality signals.
- Ranking: when someone searches, the engine selects the most relevant pages from the index and orders them according to multiple ranking systems.
SEO acts on each of these stages: it ensures pages can be crawled, helps engines understand them and reinforces the signals that justify a good ranking.
The four pillars of SEO
Although it involves many variables, SEO is usually organised into four broad areas that complement one another. None works in isolation: a technically flawless page with no relevant content will not rank, just as excellent content on a site that engines cannot crawl will not either.
| Pillar | What it covers | Examples of work |
|---|---|---|
| Technical | Access and understanding by engines | Indexing, speed, mobile, HTTPS, structured data |
| On-page | Optimization of each page | Titles, headings, internal links, images, URLs |
| Content | Meeting the needs of the searcher | Search intent, depth, E-E-A-T |
| Off-page | External reputation and authority | Backlinks, brand mentions, trust signals |
Technical SEO
Technical SEO ensures that a website can be crawled, indexed and served quickly and reliably. It is the foundation on which everything else rests. The most relevant aspects are:
Crawlability and indexing
Well-configured robots.txt files and sitemaps, no accidental blocks and a clear internal link architecture. If the engine cannot reach a page, nothing else matters.
Core Web Vitals and speed
Google measures page experience with three metrics, assessed on real user data (at the 75th percentile):6
| Metric | What it measures | Good |
|---|---|---|
| LCP (Largest Contentful Paint) | Loading speed | ≤ 2.5 s |
| INP (Interaction to Next Paint) | Responsiveness to interactions | ≤ 200 ms |
| CLS (Cumulative Layout Shift) | Visual stability | ≤ 0.1 |
In March 2024, INP replaced the former FID as the official Core Web Vitals metric.6 Continuing to optimise only for FID means working on a metric that no longer exists.
Mobile, security and structured data
Mobile-first indexing makes a site that works well on small screens essential, and HTTPS is a basic trust requirement. Structured data (schema markup) helps engines understand the meaning of content and present it in enriched ways. It is present on roughly half of the pages analysed by the Web Almanac, with JSON-LD being the dominant format.9
On-page SEO
On-page SEO is the optimization of everything within each page to make it relevant to a given topic. It includes both visible elements and behind-the-scenes elements:
- Title tag and meta description, which influence both relevance and click-through rate.
- Heading hierarchy (H1, H2, H3) that organises content in a logical way.
- Natural use of keywords and of the related terms the engine associates with the topic.
- Internal links that distribute relevance and aid navigation.
- Image optimization, with descriptive alt text and lightweight files.
- Clean, descriptive URLs.
Backlinko’s data shows that titles between 40 and 60 characters have the best click-through rate.3 A good pattern is to place the keyword on the left and the brand on the right:SEO Guide: How to Optimize Your Website | Latigid (≈48 characters).
Likewise, a URL such as /seo-tips tends to outperform /page?id=87 in clicks.
Content and search intent
At the centre of everything is content. Engines aim to serve the result that best satisfies the search intent: what the person actually wants when typing a given query.12
| Intent | What the person wants | Example search | Ideal page type |
|---|---|---|---|
| Informational | To learn something | “what is a meta description” | Article, guide |
| Navigational | To reach a site/brand | “Search Console login” | Brand page |
| Commercial | To compare before deciding | “best SEO tool” | Comparison, review |
| Transactional | To act or buy | “buy Semrush plan” | Product/pricing page |
Effective content answers the dominant intent of each search fully and clearly, and demonstrates real experience of the topic. Since the March 2024 update, Google has integrated the assessment of “helpful content” into its core ranking systems and reported a reduction of around 45% in low-quality or unoriginal content in the results.8 The message is clear: write for people, not for algorithms.
Off-page SEO and E-E-A-T
Off-page SEO concerns the reputation signals built outside the site itself. The best-known historical factor is backlinks: links from other sites to ours, interpreted as votes of confidence. More important than quantity is quality: a link from a respected, relevant source is worth far more than dozens of low-quality links.
All of this feeds into what Google calls E-E-A-T: Experience, Expertise, Authoritativeness and Trust. The first “E”, for Experience, was added in December 2022 and rewards demonstrating first-hand experience of what you write about.7 Identifying authors, citing sources and keeping transparent information about the organisation are concrete ways to reinforce these signals.
SEO in the AI era
The results page has changed. Features such as AI-generated summaries (AI Overviews) and the rise of so-called “zero-click” searches have changed user behaviour. Clickstream studies indicate that the majority of searches on Google already end without any click to the open web.2 When an AI summary appears, the likelihood of the user clicking a traditional result drops significantly.5
The good news is that the foundations have not changed. Google itself states that good SEO practices remain the path to visibility in AI features, and that there is no “special” schema nor magic files to appear in those summaries.11 Clear, trustworthy content, with demonstrated authorship and experience, technically accessible and well structured: this is what underpins both classic ranking and presence in AI-generated answers. These extensions of SEO are explored in detail on the AEO, GEO and AIO pages.
How to measure results
SEO is measured over time and with several complementary metrics:
- Organic traffic and organic conversions: the real impact on the business (Google Analytics 4).
- Impressions, clicks, CTR and average position: in Google Search Console.
- Index coverage: how many pages are actually in the index.
- Core Web Vitals: via PageSpeed Insights and field data (CrUX).
- Eligibility for rich results: validated with the Rich Results Test.
Search Console and GA4 are the free starting point; platforms such as Semrush, Ahrefs or Sistrix add keyword research, competitor analysis and position tracking.
Common myths and mistakes
“There are 200 ranking factors.” Google itself considers this number misleading, because the signals cannot be isolated or ranked by importance.10
“There is a penalty for duplicate content.” No such penalty exists; Google simply chooses a canonical version.
“Domain Authority is a Google ranking factor.” It is not. It is a third-party metric, not used by Google.
“There is an ideal keyword density.” There is not; the focus should be on user intent.
Other common mistakes include expecting immediate results (SEO is cumulative and takes months to mature), investing only in content while ignoring the technical foundation (or the other way around), chasing high-volume keywords without aligning with the real intent, buying low-quality links and failing to measure or review.
Practical SEO checklist
- The site is crawlable and indexable (robots.txt, sitemap, no accidental blocks).
- Key pages meet the Core Web Vitals thresholds (LCP, INP, CLS).
- Each page has a 40–60 character title and a unique meta description.
- The heading hierarchy is logical (one H1, with H2/H3 organised).
- Content matches the dominant search intent.
- Authors are identified and there are signals of experience and sources (E-E-A-T).
- Structured data in JSON-LD is present where it makes sense.
- Performance is monitored in Search Console and GA4.
Frequently asked questions
How long does it take to see SEO results?
It depends on the competition, the current state of the site and the effort applied, but it is common to start seeing progress between three and six months, with more consolidated results from the sixth month onwards. It is not a channel of immediate return.
What is the difference between SEO and paid advertising?
Paid advertising buys immediate visibility per click; when the investment stops, the traffic stops. SEO builds organic visibility that lasts over time, but it requires continuous work and has a more gradual effect. The two approaches complement each other.
Are keywords still important?
Yes, but the focus has shifted. It is no longer about repeating an exact phrase or reaching an “ideal density”, but about understanding the topic and the intent behind searches, covering the subject in a natural and complete way.
Does SEO still make sense with AI-generated answers?
Yes. AI features rest on the same SEO signals: useful, trustworthy and accessible content. Google itself confirms that there are no special optimizations to appear in those summaries; the foundational work is what counts. Behaviour changes (more zero-click searches), so it becomes more important to also measure awareness and conversions, not just clicks.
Sources
- Google Search Central: How Google Search works. developers.google.com
- SparkToro / Datos: Zero-Click Search Study (2024). sparktoro.com
- Backlinko: Google CTR Stats (2025). backlinko.com
- BrightEdge: Channel Share (coverage by Search Engine Land). searchengineland.com
- Pew Research Center: Google users are less likely to click when an AI summary appears (2025). pewresearch.org
- Google Search Central: Core Web Vitals (LCP/INP/CLS; INP replaced FID on 12/03/2024). developers.google.com
- Google Search Central: E-E-A-T and Quality Rater Guidelines (2022). developers.google.com
- Google Search Central: March 2024 core update & spam policies. developers.google.com
- Web Almanac 2024 (HTTP Archive): Structured Data. almanac.httparchive.org
- Search Engine Journal: Google moved on from “200 ranking signals”. searchenginejournal.com
- Google Search Central: Optimizing for AI features / generative AI search. developers.google.com
- Semrush: Search Intent. semrush.com
Note: market statistics (CTR, traffic share, zero-click searches) vary according to the methodology and time period of each study; they should be read as orders of magnitude, not absolute values.