+A **web crawler**, also known as a spider, is an [Internet](/wiki/Internet) bot that systematically browses the [World Wide Web](/wiki/World_Wide_Web) for the purpose of web indexing. It helps search engines build and maintain their vast databases by discovering new and updated pages.
+## See also
+- [Search Engine](/wiki/Search_Engine)
+- [Web Indexing](/wiki/Web_Indexing)
+- [Robot](/wiki/Robot)
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