Catch on means to become popular (a fashion, idea or habit) or to understand, when something finally clicks. In the first meaning, the subject is the idea itself: The trend caught on. In the second, it's a person, often with to: She soon caught on to the rules.
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idea/trend + catch on; catch on quickly/fast; catch on to + trick/joke/idea
- Paper straws annoyed everyone at first, but the idea soon caught on in cafés.
- The coach explained the rules once, and the kids caught on right away.
- It took my parents a while to catch on to how video calls work.
What changed
First versionEveryone laughed, but it took me a minute to catch up with the joke.
RevisionEveryone laughed, but it took me a minute to catch on to the joke.
Understanding something late can feel like catching up, but catch up with means to reach someone who is ahead or to make up for lost time, and the joke wasn't running away from you. When the meaning finally clicks, you need catch on to: catch on to the joke. The rest of the sentence stays the same.
Catch up means to reach someone or make up for lost time, often with with: I missed two lessons and need to catch up with the class. Catch on isn't about falling behind: it's the moment an idea takes hold or a person understands what's going on.
Your turn
Nobody wore these trainers last year, but the style has really ___ among students.
Show the answer
caught on — A style nobody wore last year has become popular, so caught on. Caught up means reached someone or made up lost ground, and that isn't how something becomes fashionable.
Describe a habit or app that became popular among people you know. Say when it happened.
Language exchange apps caught on among my classmates last spring, and now everyone practises with partners abroad.
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