The rate of something is how fast it happens or changes, measured by comparing it to time or another standard. When your heart beats at a rate of 70 beats per minute, that tells you how many times it beats in one minute. When a car travels at a rate of 60 miles per hour, that's its speed.

Rates help us measure and compare all kinds of changes. A student might read at a rate of 200 words per minute. A plant might grow at a rate of two inches per week. Scientists track the rate at which ice melts or populations grow. At this rate, you might think, “I'll finish this book by Friday.”

The word also means the price or cost of something. Hotels charge different rates for different rooms. Interest rates determine how much extra money you pay when you borrow, or earn when you save. A babysitter might charge a rate of $15 per hour.

To rate something means to judge or evaluate it. You might rate a movie five stars, or a teacher might rate your essay. When someone says a restaurant rates highly, they mean it gets good reviews. If something doesn't rate a second look, it's not worth your attention.