A highlighter is a marker with bright, semi-transparent ink designed to mark important text without covering up the words underneath. When you drag a highlighter across a sentence in your textbook, it leaves a stripe of vivid yellow, pink, or green that makes that passage stand out from everything else on the page.

The ink is specially formulated to be see-through, so you can still read the black text beneath the colored stripe. This makes highlighters useful for studying: you can mark key facts in your history book, important vocabulary in your English assignment, or formulas you need to remember for a math test. Later, when you flip through your notes, those highlighted sections jump out immediately, helping you focus your review on what matters most.

Students often develop their own highlighting systems, using different colors for different purposes, like yellow for main ideas, pink for definitions, and green for examples.

The word “highlight” also works as a verb meaning to emphasize or draw attention to something, or as a noun meaning the best or most memorable part of something. The highlights of your summer vacation might be the day you caught your first fish and the evening your family stayed up late watching meteor showers.