We all know that if we are developing something that runs on the web using browsers then cross-browser testing needs to be done. However, there is another variation of cross-browser testing – cross-device testing. If we have an application that is supposed to work on a device and is used by a set of people who may be using multiple devices then cross-device testing is needed.
Thus, cross-device testing here is equivalent to testing your application on multiple devices (at least all the devices that your customers might be using).