Help

I'm stuck in contextual help hell!!! 

From my amateur knowledge of photography the purpose of the hood is to prevent glare / limit lighting as in the case of outdoor photography where the sun is shining brightly in the sky.

However, I have seen photographers who always shoot with their lens hood attached, even indoors. Even if they are not using any flash.

Is there a reason why someone might want to do this?

Personally I never shoot with my lens hood on, even outdoors. I find them bulky and I don't like bringing it around attaching and detaching it all the time.

I'm starting to think it's a fashion statement to look more "pro"