Search engine optimization (Wikipedia)
Wikipedia’s article on SEO: the practice of improving website visibility in search engine results pages (SERPs). Covers history, methods, the white/black/grey hat distinction, SEO as a marketing strategy, international markets, and legal cases.
License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/
Key points
- Defines SEO as improving visibility in organic (unpaid) SERPs — distinct from paid search advertising (SEM/PPC), which prioritizes prominence over relevance.
- Traces history from mid-1990s manual index submissions through PageRank (1998), mobile-first indexing (2016), and the 2020s emergence of AI-driven search (GEO/AEO for AI-generated responses).
- Explains how search engines work: crawlers discover pages via links; XML sitemaps ensure all pages are reachable; robots.txt and
<meta name="robots" content="noindex">tags prevent unwanted indexing; root-directory distance from the homepage affects whether deep pages are crawled. - PageRank: Stanford’s Larry Page and Sergey Brin developed a mathematical algorithm rating page prominence by quantity and quality of inbound links — estimating the probability that a random web surfer following links would land on a given page.
- On-page ranking factors: keyword-rich content, title tags, meta descriptions, heading structure, content freshness, URL canonicalization, internal cross-linking, incoming backlinks, and bounce rate / user engagement signals.
- Mobile-first indexing: since November 2016 Google uses the mobile version of a site as the primary source for indexing and ranking — not the desktop version. If a site’s mobile experience is degraded, its ranking suffers across all devices.
- White hat vs. black hat: white hat techniques follow search engine guidelines and produce durable results; black hat techniques (hidden text, cloaking, link-spam networks) risk penalties or de-indexing when discovered; grey hat sits between them. BMW Germany and Ricoh Germany were removed from Google’s index in February 2006 for doorway-page cloaking; both were restored after removing the offending pages.
- International SEO: effective targeting of non-English markets requires hreflang tags, country-code top-level domains or subdirectory URL strategies, local hosting or CDNs, and transcreation (cultural adaptation beyond translation) — not simple translation alone. Covered in depth in Internationalization.
- Algorithm unpredictability: search engines change algorithms constantly (Google reported 500+ changes in 2010 alone); organic traffic rankings have no guarantee of stability, making SEO a maintenance practice, not a one-time fix.
- Wikipedia article carries maintenance notices (December 2024, September 2025) indicating some sections may be outdated.
Images
pageranks-example.png— network diagram showing how PageRank distributes authority across linked pages, with percentage-based node importance; used in Search Engine Optimization to illustrate inbound-link weightingdemystifying-seo-viz.jpg— hand-drawn mind map of SEO concepts from a 2013 WordCamp Vancouver talk; used in Search Engine Optimization as an overview illustration