What are similes used in The Perks Of Being A Wallflower?

there are no pictures in the book... but on the back of the cover when you flip the book around you see charlie making faces covering his eyes, ears, and mouth. these are like the emoji signs of the monkeys on an Apple phone or ipad. though i am not positive why that is there, i think it is to show his life. not being heard a lot (until meeting charlie and sam of course and the others), people not really "noticing" or "seeing" him, and people not talking to him a lot except for his english teacher.