What is a user agent?

A user agent is a software program that can send requests to a web server and receive responses to those requests. This is precisely what a browser does. But there are also automatic programs known as robots that are user agents. Further, web caching servers can send requests to a web server and receive responses to those requests. They generally do this on behalf of other user agents, but could in some cases do it on their own behalf (for example during pre-emptive caching) in which case they would behave like user agents. Seen from the perspective of the web server, all user agents look the same. It is not immediately obvious to the server if it is being visited by a human-driven browser or by an automated retrieval system. So we refer to all of them as user agents.

If you have any queries about internet security then please contact us.