What is SEO (Search Engine Optimization)?

The term SEO emerged in the mid-1990s, when the first search engines such as Archie (1990), Yahoo! (1994) and AltaVista (1995) started indexing web pages and the first webmasters discovered that how a page was written and structured influenced whether it showed up in results. Google's arrival in 1998, with its PageRank algorithm, shifted the starting point: instead of looking only at the words on a page, Google began weighing how many other sites linked to it and with what authority.

Since then, Google has kept releasing updates that redefine what counts as good SEO. Panda (2011) penalized low-quality content and content farms. Penguin (2012) targeted manipulated or purchased links. Hummingbird (2013) let Google understand the meaning behind an entire query, not just isolated words. RankBrain (2015) introduced machine learning to interpret new or ambiguous searches. BERT (2019) improved natural language understanding, especially for long, nuanced queries. From there, Google replaced large, one-off launches with periodic Core Updates, broad revisions to the core algorithm published several times a year without a single announced target.

This shift matters for anyone doing SEO today: before Hummingbird, optimizing for one exact keyword was enough. Afterward, a topic needed to be covered in depth and had to answer the real intent behind the search. With the arrival of AI Overviews and the rise of GEO (Generative Engine Optimization) since 2024, that gap has widened further: Google and other engines now generate direct answers drawn from multiple sources, so content has to be written in a way an AI can extract and cite, on top of convincing a human reader.

Everything starts with crawling. Googlebot, Google's crawler, moves across the web by following links from one page to another and checking the XML sitemaps sites submit to flag which URLs exist. The robots.txt file tells it which areas of the site it can and can't visit, and a clean internal linking structure makes it easier for the crawler to reach every relevant page without getting stuck in dead ends. If Googlebot can't reach a page, it simply doesn't know the page exists, and everything else in the process becomes irrelevant for that URL.

Crawling a page doesn't guarantee it gets indexed. In this phase, Google analyzes the HTML, the visible content, meta tags and structured data (Schema Markup) to decide what the page is about and whether it deserves a spot in its index, the database where it stores the pages it can show as a result. A page with thin, duplicate or technically poorly served content can be crawled without ever being indexed. A noindex tag, misconfigured canonicals or an accidental robots.txt block are the most common reasons a page never makes it into the index, even though it exists and is visible to any visitor.

Only indexed pages move into the ranking phase, the process by which Google decides in what order to show them for a given query. According to Google's own corporate philosophy page, the company assesses the importance of every web page using more than 200 signals and a variety of techniques, including the PageRank algorithm, which analyzes which sites have been "voted" the best sources by other pages across the web. Those signals include how relevant the content is to the query, domain authority, user-experience metrics such as Core Web Vitals, and the signal known as E-E-A-T (experience, expertise, authoritativeness and trustworthiness), which Google uses to try to tell content written by someone with real knowledge of a topic apart from generic content.

Search intent is the starting point of any serious SEO strategy. Before writing a single word, it's worth knowing whether someone searching a term wants to learn something (informational intent), find a specific brand or website (navigational), compare options before buying (commercial), or complete a purchase (transactional), because the same term can call for completely different content depending on the real intent behind it. Good keyword research starts by identifying that intent, not search volume on its own.

Quality content is measured today against Google's E-E-A-T framework: first-hand experience with the topic, demonstrable expertise, authority recognized by others, and trustworthiness, backed by clear contact details, cited sources and identifiable authorship. Technical SEO covers what happens underneath the content: Core Web Vitals within recommended thresholds, correct Schema Markup, HTTPS across the whole site, and a coherent, easily crawlable URL structure. Link building still works when done ethically, through Digital PR and content with its own value that other sites link to because it offers something, not by buying backlinks or forcing exchanges. Semantic content organizes pages into content clusters, a broad pillar page linked to more specific articles, to build topical authority over an entire subject rather than competing for isolated, standalone keywords. Finally, mobile-first design is no longer optional: Google indexes and evaluates the mobile version of a page primarily, so a slow or poorly adapted mobile site loses rankings even if its desktop version is flawless.

• Define the search intent behind each keyword before writing the content: informational, navigational, commercial or transactional.
• Include visible authorship, cited sources and real contact details in the content to reinforce the E-E-A-T signal.
• Check Core Web Vitals (LCP, INP, CLS) with PageSpeed Insights or Search Console and fix anything above the recommended thresholds.
• Mark up relevant pages with Schema Markup (Article, Product, FAQ) so Google can better understand the content.
• Organize content into topical clusters: a broad pillar page linked to specific articles on subtopics.
• Earn links through content with its own value or Digital PR, never by directly buying links.
• Check Google Search Console for which pages are indexed and which have been excluded, and why.
• Optimize the mobile version of each page first: it's the one Google indexes and evaluates by default.

• Optimizing for one exact keyword without considering the real search intent behind it.
• Accidentally blocking important pages in robots.txt or marking them noindex after a template change.
• Buying links or joining mass link-exchange networks, risking a manual penalty.
• Publishing generic content or content rewritten from other pages without real experience or added value.
• Ignoring Core Web Vitals until performance is already visibly hurting rankings.
• Duplicating content across similar pages without defining a clear canonical URL.