Triangles

Ok i will just warm you in advance this is a really random post :/ but there are just questions that need to be answered, so as none of my friends no anything about the subject i thought i might just blog about it :) Well anyway my question is what are these Triangles? i see them on tumblr and weheartit but have never quite understood them :/ i guess they are just some internet sensation that someone thought up. I dunno but any comments, and i would be great full :) lots of love xxxx Elliott smith -between the bars