A user-agent is defined as the client application, or computer system, that is used with a particular network protocol, such as the World Wide Web. In broken down terms, the user-agent is the computer system’s application that is remotely accessing another computer, or server, via the network. In most cases your web browser is the user-agent and the network is the Internet. In fact, this sort of system to system communication is referred to as client-server, and it is used by the Internet: it means that a user (such as your web browser) accesses a program or service that is operating on another, remote, system (a web page) via the internet protocol of that system (the web page’s server).