You may have given test builds to friends and colleagues all the way through the process of developing your app, but even if you haven't, it becomes more important to do so as you get closer to the time when you have to upload the app to the app stores. Beta testers can tell you about technical and nontechnical issues. Are there any typos in the Credits? Does the icon look good? Were there any strange aspects to the installation experience? And of course, does the app do what it's supposed to do on the numerous devices and OSes?
The process of making an app to send it to a tester is different on Android than on iOS. In fact, it's incredibly easy on Android! Let's look at that first.