When you annotate something, you add notes, comments, or explanations to it. Students annotate books by underlining important passages and writing thoughts in the margins. Scientists annotate their data with observations about what they found. Musicians annotate their sheet music with reminders about tempo or dynamics.

The word comes from Latin words meaning “to mark” or “to note.” An annotation is the note itself: the little comment you scribbled, the arrow you drew, or the question mark you added. Think of annotations as your conversation with a text. When you write “Wait, what?” next to a confusing paragraph or circle an unfamiliar word to look up later, you're annotating.

Teachers often ask students to annotate what they read because it helps you engage more deeply with the material. You might note patterns you notice, questions that arise, or connections to other things you've learned. A well-annotated text becomes more useful over time, filled with your own thinking and discoveries layered on top of the original words.