There's an Apple iPhone feature that you might turn on by accident from time to time. As you can see in the picture above, it just looks like a rectangle that sits on your display and gets in the way of everything.
This rectangle actually has a purpose. It's called "Zoom" and is used to magnify certain parts of the screen. If it's active, the rectangle will appear if you double tap the screen with three fingers.
It isn't immediately obvious how to get rid of it. The easiest way is to tap the screen twice with three fingers again. You can also tap the small white oval in the bottom center the rectangle, which brings up a set of menu options. Then hit "zoom out" and it'll disappear.
The feature can actually be pretty useful, especially if you're reading a screen full of tiny text.
But if you keep getting the rectangle by accident, you can turn it off so that doesn't happen.
- Open Settings.
- Select Accessibility.
- Toggle the "zoom" option to off.
Everything should look like this now: