Glasses are a pair of lenses held in a frame that you wear on your face to help you see more clearly. If you're nearsighted, glasses help you see things far away, like the board at the front of your classroom. If you're farsighted, they help you see things up close, like the words in a book. Some people need glasses for reading, others wear them all the time, and some only need them for specific activities like watching movies or doing detailed work.

The lenses in glasses are carefully shaped pieces of glass or plastic that bend light in specific ways to correct how your eyes focus. An eye doctor called an optometrist tests your vision and writes a prescription that tells the lens maker exactly how to shape your lenses. Everyone's prescription is different because everyone's eyes are unique.

Glasses have been around for about 700 years. Early versions were clumsy and expensive, but today's glasses are lightweight, comfortable, and come in countless styles. Some people call them spectacles or eyeglasses, and the lenses themselves are sometimes called specs.

People also use the word glasses for drinking vessels, like a glass of milk or a set of glasses in the kitchen cabinet, but those are completely different from the glasses you wear.