Tumblr. If you think that's a typo you're probably not a user of this easy-to-populate blog site.
In its own words: "Tumblr lets you effortlessly share anything. Post text, photos, quotes, links, music and videos from your browser, phone, desktop, email or wherever you happen to be."
Big whoops, you say. I can do that on Facebook, you say. Why should I care?
If you're relatively young (and that's all in the mind of the beholder, isn't it?) you may like to know that Tumblr has the youngest overall demographic, with a bigger proportion of 18-24-year-olds favouring the site over rivals such as Facebook, Pinterest and Twitter. It's where the cool kids are hanging out.
If you're a parent, you should care because Tumblr may be where your kids are escaping to in order to avoid you.