On lower memory devices, or ones with overly heavy Android skins, RAM can be a precious resource, even though Google's OS operates best when most of it is filled. In many cases, overflowing RAM will cause Android to take drastic measures, such as killing off apps it deems least likely that you'll use next. As you can imagine, that's not a necessarily desirable outcome.
But what if you have a ton of apps, and you just can't figure why all of a sudden your device is acting out? In those cases, you'll need to investigate, and that's made easier than ever with Android 6.0 Marshmallow's Memory tool. Here's how to make sense of it and use it.