Internet robots are known by many names — bots, spiders, web bots, robots, and crawlers. What all bots have in common is that they are software applications or scripts. Where they differ is in the tasks that they perform. They're purpose or benefit is simple: to quickly complete jobs, especially repetitive ones.

Bots are most commonly used in indexing on a search engine. When used for this purpose bots are programmed to visit sites on the Internet for use on search engine results pages. That is, the hits that you get the next time you perform a search on your favorite search engine will be there, in part, because a bot went out and identified that site. Bots run periodically to make sure that the webpage still exists and is still relevant to a given topic. These bots are known as web bots, web spiders, or a web crawlers.

Web bots will also collect links from the website it visits and add those to the list of sites to visit. If you have heard that it is important to get other sites to link to yours, this is why. The more hyperlinks of your URL there are the better your site will be rated by search engines. In addition, bots can be used to check links on a website to make sure they are directing clicks to the right location and look for errors in HyperText Markup Language (HTML) code.

Bots can be used for less appealing purposes as well. They can be used, for example, to visit websites to collect data such as e-mail addresses. These e-mail addresses can then be used to send out mass emails of spam — messages that are sent without consent.

Other functions of bots include interactive interfaces used in Instant Messaging (IM) services. Advanced bots, also called chatter bots, may be able to communicate requested information to a user such as time, date, or weather. Some are used to censor and monitor profanity usage.

If you have ever wondered how a concert can be sold-out in record time, it is likely bots have been employed. These bots allow the purchaser to buy large numbers of seats in a very short period of time. Similar bots are also used on auction sites and some online gaming sites.