What is a User Agent String?
A user agent string is a string of text that is sent by a web browser or other web client to the web server it’s connecting with. It identifies the browser, the operating system, and the version of software being used. It helps the web server determine what content to send to the user.
How do User Agent Strings Work?
When a user connects to a web server, the server can access the user agent string and use it to determine the type of web browser connecting. This information can then be used to display the most appropriate version of a website for the visitor’s device. For example, if the user agent string identifies that the visitor is using an outdated version of a web browser, the server can send them a version of the website optimized for their device.
Examples of User Agent Strings
Here are some examples of user agent strings:
- Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.111 Safari/537.36
- Mozilla/5.0 (iPhone; CPU iPhone OS 14_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.0 Mobile/15E148 Safari/604.1
- Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.111 Safari/537.36
As you can see, these strings contain information about the type of device and web browser being used.
Conclusion
User agent strings are a useful tool for web servers to determine what content to send to a visitor. By understanding how user agent strings work, web developers can create websites that are optimized for any device.Further Reading: