When you open a website in your web browser, the web browser sends a unique string to the web server that can be used to identify your web browser. This string is called the user-agent string is different for all the different web browsers. Even for the same web browser (e.g. Chrome), it varies for different versions and platforms. Through the user-agent string, a web site can know about your web browser, the version of the browser, the web rendering engine used, and the operating system. Based on this information some websites deliver you a different set of web pages, for example, if you visit the Firefox browser download website, it will automatically show you the Firefox browser downloads for your operating system.
By changing the user-agent string, you can change the browser identity for your web browser. This can be achieved for the Chrome web browser using the Random User-Agent extension. Unlike some of the similar extensions of the same type, this extension changes the user-agent string automatically. The reason for this as explained by the author is to anonymize yourself from a number of websites. So basically by using this extension, you can hide yourself from some of these websites.
The extension installs an icon in the Chrome toolbar clicking on which you can view the currently used user-agent for the Chrome web browser, enable/disable the extension, pause the extension, get a new agent and so on. From here, you can also open the extension settings.
The settings also have a number of user-agent strings that you can pick for randomly picking for Chrome. In order to use these user-agent strings, you can just place a check-mark against these user-agent strings (actually the web browser names and their versions). You can also add domain name exceptions for which the user-agent string is never changed.
Conclusion: Random User-Agent extension for Chrome allows you to hide your web browser identity by randomly switching the user-agent strings from a pool of user-string selected by you. It can be useful if you want to stay anonymous on the internet.
You can get the Random User-Agent for Chrome from https://chrome.google.com/webstore/detail/random-user-agent/einpaelgookohagofgnnkcfjbkkgepnp?hl=en.