Internet robots are known by many names — bots, spiders, web bots, robots, and crawlers. What all 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, they are programmed to visit sites on the Internet for use on search engine results pages. That is, the hits that a user gets when he or she performs a search on his or her favorite search engine will be there, in part, because a bot went out and identified that site. They run periodically to make sure that the webpage still exists and is still relevant to a given topic. These 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. This is why many people believe that it is important to get sites to link to each other. In some cases, the more hyperlinks of one URL there are, the better that site may be rated by search engines. In addition, these applications 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 these scripts 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.
People who have wondered how a concert can be sold-out in record time may be interested to know that it is likely bots have been employed. These allow the purchaser to buy large numbers of seats in a very short period of time. Similar scripts are also used on auction sites and some online gaming sites.