User Agent
A user agent is a text which is sent by your web browser or other client software to identify your device to a website that you're visiting. The user agent typically includes information about the your device client software, such as the name and version of the web browser or device, as well as information about the operating system and hardware of the client and your IP.
The user agent string is part of the HTTP request headers that are sent by the client to the server when a web page or other resource is requested. Web servers can use the user agent string to tailor the content that is served to the client, based on factors such as the capabilities and preferences of the client software.
For example, a web server might use the user agent string to detect that a client is using a mobile device with a small screen, and serve a simplified version of a web page that is optimized for mobile viewing. Alternatively, a web server might use the user agent string to detect that a client is using an older web browser that does not support modern web standards, and serve a fallback version of a web page that is compatible with the older browser.
Here are the information that your browser just send to my website.