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SEO Term Definition

SEO (Search Engine Optimisation)

SEO is the practice of improving a website's visibility in organic (unpaid) search engine results through technical, on-page, and off-page optimisation.

Reviewed by Alexander Yarovenko · Updated: 2026-09-22

What is SEO?

SEO (Search Engine Optimisation) is the process of improving the quantity and quality of organic traffic to a website from search engines like Google and Bing. It encompasses three main pillars:

  • Technical SEO — ensuring search engines can crawl, index, and render the site efficiently
  • On-page SEO — optimising content and HTML elements (title tags, headings, meta descriptions) for relevance
  • Off-page SEO — building authority through backlinks and brand signals

How Search Engines Work

  1. Crawling — search engine bots discover pages by following links
  2. Indexing — pages are processed and added to a searchable database
  3. Ranking — the algorithm orders pages by relevance and authority for each query

Why SEO Matters

Organic search typically drives 50–60% of all website traffic. Unlike paid ads, organic rankings continue generating traffic without per-click costs. A well-optimised site compounds authority over time, making each incremental effort more valuable.

Editorial decision

SEO improves discovery and understanding for search and users; it cannot guarantee indexing or positions.

Validation

Check technical access, useful content, search appearance, links and measured outcomes on representative live pages and record the result.

Primary references