bots are automated coding that is designed to do something in the cyber world. the google bot is a helper bot, it lists our site on google to increase traffic. if you use mIRC, an older chat program, you can type certain commands and a bot will respond with lists or help to automatically download files via FTP instead of an live person admin/moderator doing it.
there are also bad bots, which will register and spam your sites, hence the porn ad posts we use to occasionally see in the old site.