This is an automated software program that can execute certain commands when it receives a specific input (like a ro-"bot"). Bots are most often seen at work in the Internet-related areas of online chat and Web searching. The online chat bots do things like greet people when they enter a chat room, advertise Web sites, and kick people out of chat rooms when they violate the chat room rules. Web searching bots, also known as spiders and crawlers, search the Web and retrieve millions of HTML documents, then record the information and links found on the pages. From there, they generate electronic catalogs of the sites that have been "spidered." These catalogs make up the index of sites that are used for search engine results.