Someone who believes that they are being unique and non-conformist, while in actuality they are all the same. Hipsters, while stressing individuality, all like the same general things: combat boots, cross jewelry, mermaids and american flag apparel for girls; skinny jeans and beanies for guys. Hipsters try so hard to be different that they are actually all alike. Hipsters most likely have a tumblr.
I'm such a hipster, I listen to indie music that nobody else has heard of, and buy all my clothes from vintage stores that nobody else goes to.