However, there are some cases in which publishers need to communicate more information to search engines — like the fact that they don’t want certain content to appear in search results. And for that they use something called the Robots Exclusion Protocol (REP), which lets publishers control how search engines access their site: whether it’s controlling the visibility of their content across their site (via robots.txt) or down to a much more granular level for individual pages (via META tags).

Since it was introduced in the early ’90s, REP has become the de facto standard by which web publishers specify which parts of their site they want public and which parts they want to keep private. Today, millions of publishers use REP as an easy and efficient way to communicate with search engines. Its strength lies in its flexibility to evolve in parallel with the web, its universal implementation across major search engines and all major robots, and in the way it works for any publisher, no matter how large or small.

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