The word do is one of the most versatile and hardworking words in English.

At its most basic, do means to perform an action or complete a task. You do your homework, do the dishes, or do a cartwheel. When someone asks “What are you doing?” they want to know what action you're performing right now.

But do also functions as a helper word that makes questions and negatives possible. Instead of saying “You like pizza?” we say “Do you like pizza?” Instead of “I not understand,” we say “I do not understand” (or “I don't understand”). Without do, English would sound strange and choppy.

The word pops up in countless expressions. When something will do, it means it's good enough, even if not perfect: “This pencil will do.” When you make do, you manage with what you have. To do away with something means to eliminate it. A to-do list tracks tasks you need to complete.

Do can even be a party: someone might host a fancy do for a special occasion.

Because do appears so frequently and means so many things depending on context, it's sometimes called a “light verb.” It carries the grammar while other words carry the main meaning, like when you say you do your best or do someone a favor.