It DEFINITELY depends on the device, but it's usually something easy so it's worth taking a few minutes to google your device. On my Samsung Galaxy S3 phone, you could simply wipe your hand from left to right on the screen to take a screenshot, but this feature had to be specifically enabled. On a Galaxy Note 10.1 tablet, touch and hold the stylus anywhere on the screen and it saves a copy to your screenshots folder as well as puts it in the clipboard. There is also a "quick launch" icon on the Galaxy Note 10.1 so you can press a single button. On the Galaxy Note 4, you hold down the power and home button simultaneously - not exactly intuitive, but once you know the trick, it's quite easy.