Tumblr is like a cross between a blog and Twitter: It's a streaming scrapbook of text, photos and/or videos and audio clips. Users create and follow short blogs, or "tumblelogs," that can be seen by anyone online (if made public).
Why it's popular
Many teens have tumblrs for personal use -- sharing photos, videos, musings and things they find funny with their friends. Tumblelogs with funny memes and gifs often go viral online, as well (case in point: "Texts from Hillary").
What parents need to know
On the safety side of things Tumblr keeps things simple. The only information they ask of you during sign up is what’s shown in the screenshot above. However, as soon as you hit start you’re asked to type in your age, and if you type in anything below 13 Tumblr rejects your registration. This means, and as Tumblr’s Terms of Service makes clear, children 12 and under are not allowed on Tumblr.
Porn is easy to find. This online hangout is hip and creative but sometimes raunchy. Pornographic images and videos, depictions of violence, self-harm, drug use and offensive language are easily searchable.
A simple tag search for “porn”, “sex” or “adult” results in a stream of pornographic images and video that any Tumblr user can see and share.
Privacy can be guarded, but only through an awkward workaround. The first profile a member creates is public and viewable by anyone on the Internet. Members who desire full privacy have to create a second profile, which they're able to password protect.
Posts are often copied and shared. Reblogging on Tumblr is similar to re-tweeting: A post that's reblogged from one tumblelog then appears on another. Many teens like -- and in fact, want -- their posts reblogged. But do you really want your kids' words and photos on someone else's page?
Despite it being a creative outlet for young minds, the fact remains that Tumblr is not for children. Websites like Facebook, Twitter and Tumblr can only go as far as requesting their age during registration; it’s in your hands to educate your child about following the rules, whether it’s in school, on the soccer field or online.