The term cross-browser testing usually means some variation of testing of a web-based application on different browsers. We might have a requirement that our application must run on Internet Explorer, Firefox, Chrome, and Safari. Conversely, we might have to support all versions of Internet Explorer from version 8 and later. And what do we mean by “must run”? Is it enough that the functionality is identical on different browsers? What about the way the page looks—is it acceptable if two buttons appear on the same line in one browser, but appear one above the other in a different browser?