It's empowering to decorate in a way that communicates to you and to other people parts of your personality you're proud of and parts of life you may find universal or things that are important to you. One of the ways you can tell yourself 'I Love You' is by using a theme that helps you and reminds you of what's true, or what's important, or what's beautiful, or what's transcendent. That can be a little bit of symbolism. It can be more directly relating to something spiritual. Or it can be something fun! For me, the background is important! I want an image that doesn't downgrade me, so I'm choosy for mine. A background is one thing, and a theme is another. Themes apply a different look to everything on your phone except its menus (I think). If you haven't used it before don't hesitate, BUT... Finding your way back to default can be pretty tricky. Try an Autumn one or Thanksgiving or Christmas or Paradise or Nature or Cars. If you like what it does, don't stop there! If you don't like it, unfortunately it's difficult to get back where you were. You can ask your PC for instructions, and it can be done but it isn't very intuitive. Getting back to square one requires some digging. And Samsung isn't the only one. I'm sure Apple has something, but I've never tried iPhone myself. Xiaomi has 1,000,000 backgrounds! But I don't remember if theirs has themes, though I think so. Pixel's are hidden and 3rd party for now. Motorola maybe is this way too.