What is done in user testing? There are several types of user testing. The main point of user testing is to identify how a user will use your site and whether or not your site features meet the users needs. User testing can be done as the site is being developed to understand the user perspective and needs. Usability testing is done after the site has been developed to understand how the user interacts with the site as a working platform. There are many companies that offer usability testing and there are sites that users can sign up to test sites. Some of the things that are discerned is the actions of the user on the site: where and how do they move through the site, how do they respond to certain aspects of the site, and is the site intuitive to the user.
How are different versions of browsers tested? Browser testing is a separate issue. Browser testing understands how the site will act when used across different browsers and across different versions of those browsers. As with user testing, there are many companies that offer browser testing, and with help to fix bugs that happen in various browsers and versions. In 2013 W3C started a Web-Platform-Tests project. This was a huge undertaking and has now been succeeded by web-platform-tests.org. With the constant evolution of the internet, it is important to understand and develope sites that can withstand the everchanging environment of the web and to build sites that will be forward compatable with the new changes that will come along. To test your site on the web you use something called a runner.