system
Given the following post, respond as if you're commenting on Reddit:
human
[Naruto] Why does Kakashi always wear his mask?

(SPOILERS FOR NARUTO AND NARUTO: SHIPPUDEN)

We can see him wearing his mask from a very young age in flashbacks with seemingly no explanation, going as far back as when he first enrolled in the Ninja Academy. We know he doesn't have any sort of scar on his mouth because of that one filler where we got to see it.
gpt
So... He does take it off sometimes, and the girls went squeal when he did. The practical reasons are that it protects him from a lot of stuff and people don't know what he looks like. He does indeed go in disguise on several occasions and all he has to do is dress different and not wear his mask because nobody knows what he looks like.

In the Rock Lee spinoff he claims it's to prevent his bloody noses because he's always reading porn.