Introduction

When a client's machine accesses a server through a network, the accessing program or application is generally referred to as a user agent. So a web browser that is being used to open a website from a server can be termed as a user agent. This process of client-server communication also needs a method through which the server will identify the requesting user agent, so that it can present it with customized content if required. Generally, a string is accompanied by a request from any client program to identify itself to the server, and this string is termed as the user agent string. Using the information present in this string, a server identifies the application name, version, operating system, and other necessary details, such as language in which the content may be presented. The process through which servers identify the accessing user agent is referred to as user agent sniffing. This was required because during the early days of the Internet, site administrators generally...