Why does Kakashi Hatake always wear a mask? Since his childhood as depicted in manga/anime, Kakashi always wore a cloth mask covering his face, making only eye(s) and a portion of forehead visible.

What was the reason for this?
I have collected a few reasons, which are actually assumptions..


Because he was an ANBU. All the members of ANBU wear masks for various reasons. (hiding their identity, their feelings, expression, and so on, making them merely fighting robots) 
Since his childhood days, he always was looked down on by the villagers because his father sacrificed a mission in order to save his comrades. This resulted in a huge loss to the village (maybe in terms of reputation and economy). He wanted to hide himself.
Moreover, people could easily mistake him for his father since they look similar (one example: Lady Chio attacking Kakashi Hatake because she mistook him for his father Sakumo).  He tried to hide himself with his mask, though people vaguely remember it since a generation has been passed.


Though all the above reasons aren't really valid now (in both the anime and manga), Kakashi still wears mask, for which the reason is unknown.


Just an idea Kishi had. And here is a piece of information from a blog:



  In an interview the question, "Why does Kakashi wear a mask?" was asked. Kishimoto's reply was that he saw ninjas as being "mysterious" or something, so in his character design he made Kakashi wear a mask, but he didn't do that with other characters because it's too difficult to get their expressions down when you can't see their entire face.


Blog link: [click here]