It's like reddit but friendlier, or 9gag but not 9gag because 9gag sucks hairy balls, its like 4chan but not soul eating, its everything you could want in a website and more. Imgur is a great place to spend an afternoon.
Also it has a lot of cats...A LOT of cats.
"Hey man you been on imgur lately?"
"Yea dude you see that post about the ____?"
"Yea dude, i was laughing for hours!"