A system that is embedded in an environment, and takes actions to change the state of the environment. Examples include mobile robots, software agents, or industrial controllers.
A piece of software, such as a browser or spider, that interprets the content on a web server and presents it to the user as a web page. Examples include Internet Explorer, Opera, Netscape and various search engine spiders. Examples: MS Internet Explorer, Netscape Navigator, Googlebot, Slurp, T-Rex