If your iPhone storage has nearly filled up, cache could be to blame. As you use more apps, they require more space on your phone to store information. Luckily, you can clear cache in your iPhone or iPad easily. We’ll take a look at how to clear cache on your iPhone, and what clearing cache does. What Is Cache? Cache is a term for temporary data stored by apps and websites so they can work more efficiently in the future. For example, if you visit a website with a large banner graphic, your browser will cache that so you don’t have to download it again next time you open that page.