Mostly known by the general public because of "hipsters" and it's also where "planking" began.
Tumblr is the most amazing website, designed to bring lovely people together. Those who had tumblr before it was cool will know that it is "the easiest way to blog" and the most incredible website ever known to man, woman, animal, etc.
So basically, on tumblr, you follow people and I guess you want people to follow you. Then on your dashboard you see everything that everyone you follow posts. You can then "heart" or "reblog" a post that you think is rad. Reblogging will put the post onto your blog. And giving it a "heart" makes it go into a little section called "liked posts" which is pretty much a collection of the greatest things you've ever discovered on this site. However, nobody but you can see this collection.
Tumblr will either:
A. Ruin your social life, school work, friends, family relations, sexual relationships and even relationships with pets. (Take over your life)
B. Make you feel horrible about your body because your bones don't stick out enough.
C. Annoy the heck out of you because you can't figure out to use it.
D. Be the best thing that ever happened to you.
OR all or a combination of the options.
"I really love tumblr but I can't stop going on it. I'd rather look at pictures of cats then play with my real life cat, so my cat gets angry at me. "