Search Engine Optimization (SEO) is a set of practices aimed at improving a website's visibility in search engine results pages. It involves technical optimization, content creation, and authority building to align with Google’s Search Essentials and user intent.

Definition and Scope

SEO is defined by Google as helping search engines understand content while assisting users in finding relevant informationGoogle SEO Starter Guide. Eligibility to appear in Google Search requires compliance with technical requirements, spam policies, and best practices outlined in the Search EssentialsGoogle Search Essentials.

Technical Controls

A robots.txt file instructs crawlers which URLs may be accessed but does not prevent indexing of disallowed pagesRobots.txt Documentation. For sensitive content, the noindex directive or authentication is recommended. XML sitemaps convey the structure and priority of site pages to crawlers, improving crawl efficiencySitemaps Overview.

Ranking Signals and Page Experience

Core Web Vitals—Largest Contentful Paint (≤ 2.5 s), Interaction to Next Paint (≤ 200 ms), and Cumulative Layout Shift (≤ 0.1)—are incorporated into Google’s ranking algorithmsPage Experience GuidelinesWeb Vitals Thresholds. While other page‑experience factors aid user satisfaction, they are not direct ranking factors.

Content Quality – E‑E‑A‑T

The Search Quality Rater Guidelines emphasize Experience, Expertise, Authoritativeness, and Trustworthiness (E‑E‑A‑T) as criteria for high‑quality contentSearch Quality Rater Guidelines. Raters evaluate content but do not directly influence algorithmic rankings.

Algorithm Updates

Google regularly rolls out core and spam updates. Notable recent updates include the March 2024 core update (45‑day rollout)Google Ranking UpdatesMarch 2024 Blog and earlier updates such as Panda (2011), Penguin (2012), Hummingbird (2013), RankBrain (2015), and BERT (2019)Algorithm HistoryAlgorithm Updates.

Historical Foundations

Google’s 1998 research paper introduced PageRank, a link‑analysis algorithm that formed the basis of modern web searchAnatomy of a Large‑Scale Web Search Engine. The evolution of search engines is chronicled in encyclopedic sources, noting SEO as an ongoing practice to influence visibilityBritannica – Search Engine.

Market Share Context

As of January 2026, Google commands approximately 89.82 % of global search traffic, underscoring the importance of SEO for most web publishersStatCounter Market Share.

Core Practices

Key SEO activities include keyword research, meta‑tag optimization, structured data implementation, link building, and performance monitoring. Guides such as the Moz Beginner’s Guide provide detailed tactics for each areaMOZ Guide.

Internal Links

Relevant concepts include Google Search, PageRank, Core Web Vitals, Search Engine Results Page, and Search Engine Marketing.