When you look, you focus your vision on someone or something. If you get to the movie late, you'll have to look for your friends in the darkened theater.
The Old English word locian is the root of look, meaning "see, gaze, or spy." When you look at something, you see it. Look can also describe how something appears, like when your dog looks sad, or something likely to happen, like a gray day that looks like rain. As a noun, look describes someone's style of dress, like your brother, whose rock star look gets lots of compliments — except from Grandpa.