A user agent is a software element that acts on behalf of the user in a network service. Web browsers, email-readers, IRC clients, search robots can serve as examples of user agents. It is usually employed for using the information in order to carry out the following functions:
- Improving email campaigns by adapting HTML emails to different devices.
- Providing users with a relevant version of a particular website in case of using a mobile phone.
- Defining whether a website is up-to-date or in need of any modification.
- Collecting information for statistical objectives.
- Performing content negotiation on the basis of the already acknowledged capabilities of a particular version of the software
There exists a division of user agents into types:
- Web browser. This is a software program used to access and view various websites.
- Web application. This is a client-server application in which the client interacts with the web server using a browser.
- Spider. This is an Internet bot that surfs the World Wide Web and conducts text indexing on different websites.
