ELI5: Explain Like I'm 5

why some people have dandruff

Dandruff happens when the skin on your scalp gets dry and flakes off. It can be caused by lots of things, like not washing your hair enough, or using the wrong kind of shampoo. It can also be caused by not eating right, or not getting enough sleep. All of these things can make your scalp irritated and cause dandruff.