SSD-0001 · Status: stable · Version 1.0 · Reviewed 12 November 2026 · Wikidata Q180711
Definition
Search engine optimization (SEO) is the practice of adjusting a site’s content, structure and technical signals so that search engines can crawl, index and rank it for the queries it is meant to answer.
搜尋引擎最佳化（SEO）是指調整網站的內容、結構與技術訊號，使搜尋引擎能檢索、索引，並就網站真正能回答的查詢給予排名。
In practice
SEO is usually split into four workstreams that fail independently: technical (can a crawler reach and render the page), content (does the page answer a real query better than what already ranks), authority (does anything outside the site vouch for it), and measurement (can you tell whether any of it worked). Since 2023 a fifth has joined them: whether a page survives being quoted inside a generated answer. SEO is a means, not an end — the end is qualified organic traffic that converts, and those are not the same number.
實務上，SEO 通常分成四條會獨立失效的工作線：技術（檢索器能否到達並渲染頁面）、內容（頁面是否比現有排名者更好地回答一個真實查詢）、權威（站外是否有任何東西為它背書）、量度（你能否判斷以上是否有效）。2023 年後多出第五條：頁面能否在被生成的答案引用時仍然成立。SEO 是手段，不是目的——目的是會轉換的有質素自然流量，而兩者不是同一個數字。
What it is not
- Not SEM. Search engine marketing is the paid side of the same results page. SEO is the unpaid side. They share real estate, not a budget.
- Not “ranking first”. A ranking is a position; SEO is the practice. A first position that matches the wrong intent produces traffic that never converts.
- Not a one-off project. Rankings decay as content ages and competitors improve. The work is maintenance as much as launch.
- Not a synonym for GEO or AEO. Those name a narrower goal — being cited inside a generated answer. They are a subset of the visibility problem, not a replacement for it.
Status
Stable. The term has been in continuous professional use since the late 1990s and its meaning has not materially shifted. What has shifted is the surface being optimized for: from a page of ten links to a results page that increasingly answers the question itself.
Identity
- Wikidata: Q180711 — search engine optimization
- English aliases: SEO; search engine optimisation (British spelling); organic SEO
- 中文正名：搜尋引擎最佳化（香港、台灣）；中國大陸作「搜索引擎优化」
- Primary official source: Google Search Essentials
Related terms
- Search engine results page (SERP)
- Organic search
- Search intent
- Crawl budget
- Generative engine optimization (GEO)
- Answer engine optimization (AEO)
Sources
- Google, Google Search Essentials, developers.google.com/search/docs/essentials (accessed 12 November 2026).
- Wikidata, item Q180711 “search engine optimization” (accessed 12 November 2026).