User-Agent
What is a User Agent?
A User agent is a type of software that performs actions on behalf of a user when interacting with the web. The most common examples of a user agent are browsers like Chrome or Firefox. However, other clients, such as bots or download tools, can also be a User agent. When you browse web pages, the User agent communicates with web servers to request web contents and deliver it to your device.
How User Agent Works in Browser?
When you open a web page, the browser sends an HTTP Useragent header in its requests to the server. That useragent string contains details about the operating systems, the browser version, and the device in use. This makes identifying users’ OS and browsers easy for web servers.
The User Agent helps websites or web servers provide different contents based on the browsers or mobile devices users are using. This helps enhance user experiences.
User Agent’s Structure
A User Agent typically contains agent strings, which are made up of product tokens and comments. The structure often includes the browser name/version and OS info. The servers parse these User Agent strings using request headers to identify clients. Based on these strings, servers decide to serve mobile versions or full desktop versions of the content.
User Agent Examples
Here are a few User agent examples representing different browsers and devices:
- Mozilla/5.0 (Windows NT 10.0; Win64; x64) Chrome/124.0.0.0 Safari/537.36
- Mozilla/5.0 (iPhone; CPU iPhone OS 17_0 like Mac OS X) AppleWebKit/605.1.15 Mobile/15E148 Safari/604.1
- Mozilla/5.0 (Linux; Android 14; Pixel 8) AppleWebKit/537.36 Chrome/124.0.0.0 Mobile Safari/537.36