Here are a few highlights. On age restrictions:
You have to be at least 13 years old to use Tumblr. We’re serious: it’s a hard rule, based on U.S. federal and state legislation. “But I’m, like, 12.9 years old!” you plead. Nope, sorry. If you’re younger than 13, don’t use Tumblr. Ask your parents for a Playstation 4, or try books.
On content ownership:
One thing you should consider before posting: When you make something publicly available on the Internet, it becomes practically impossible to take down all copies of it.