Why Do Smartphones Get So Hot When You're Using Them?

Smartphones get hot because they work really hard when you're using them. Imagine your phone is like a little person running around doing lots of things at once, playing games, talking on the phone, and maybe even watching videos. That makes it feel like a warm hug. When your phone uses its energy quickly, like when you're gaming or taking selfies in the sun, it heats up because it's working so hard. Just like how you might feel warm after running around.