noindex
A meta instruction telling the engine not to include a page in the index, while still allowing it to be crawled and its links followed.
Analogy Mental model
A file stamped not for public release. It stays in the cabinet, and nobody finds it by searching the catalogue.
In practice What you actually do
Use it on thank-you pages, internal search results, tag archives that duplicate categories, and staging environments. The page must be reachable by a link, otherwise the crawler may never see the instruction it is meant to obey.
Where people get burned Pitfalls
noindex and disallow contradict each other. If the page is blocked in robots.txt, the crawler cannot read the noindex, and a page already indexed can stay there for months because it was never recrawled.
This entry was written in English from the Chinese original, not machine-translated. Read the Chinese version →