Either is a word that points to one of two choices or possibilities. When your teacher says “you can either finish your math homework or start your reading assignment,” she means you get to pick one option or the other, but not both. When your dad says “take either path through the park,” both routes will work.

The word can also mean both of two things. If you have cookies on either side of your plate, you have cookies on the left and the right. When someone sits on either end of the bench, people are sitting on both ends.

You'll often hear either paired with or: “Either we leave now or we'll be late.” This construction presents two alternatives. The negative version uses neither with nor: “Neither the library nor the cafeteria is open,” meaning both places are closed.

One tricky aspect: either technically refers to just two options. If someone offers you three desserts and says “pick either one,” they're using the word loosely. The traditional choice would be “pick any one.” But in casual conversation, people use either even when more than two options exist.

When you're writing and want to present two clear alternatives, either...or gives your reader a structured choice that's easy to understand.