A tablet can mean two different things:

1. A small, flat computer you can hold in your hands and control by touching the screen. Unlike a laptop, tablets don't have a keyboard attached (though you can connect one if you want). You tap, swipe, and pinch the screen to open apps, read books, play games, or browse the internet. Today, millions of people use tablets for reading, drawing, taking notes, or watching videos. They're portable like a book but can do many of the same things a computer can do.
2. A solid piece of medicine shaped like a small disk that you swallow. When a doctor prescribes medicine in tablet form, you take it with water. Some people call these pills, though technically tablets are compressed and formed into shape, while pills can also be soft capsules.

Ancient people also carved writing onto stone or clay tablets before paper existed.