The site I used to find what user testing was is https://www.omniconvert.comand a website that also explains it https://www.agconsult.com/en/usability-blog/user-testing-what-why-and-how/. The difenition of User Testing in my words are, real people fill out serverys,emails and test things on websites so the developers can use that information to make a sturdier website for different versions of web browsers.