Just like the rest of the Internet, Vine has plenty of cats.

Screen shot by HowStuffWorks staff

In this age of instant over-sharing, it's not at all surprising that teensy, short-form videos are going viral. And as so often happens, it wasn't an established technology company that started the trend -- instead, it was a startup called Vine.

Vine is an app for mobile devices that lets you capture video in six-second bursts. Then, you can immediately share your creation with the entire Vine network. In short, Vine is like the video version of its terse, text-driven cousin Twitter. Appropriately, Twitter bought Vine in late 2012.

The brainchild of Dom Hofmann, Rus Yusupov and Colin Kroll, Vine debuted in 2012 as an app for iOS devices. By June 2013, it was available for Android, too. The backing of Twitter caused an explosion in Vine's popularity -- it soon became the most popular video-sharing app and a mainstay in lists of top 10 free apps. By the middle of 2013, in fact, more than 40 million people had signed up for free Vine accounts [source: Rodriguez].

The multitudes didn't mess around. They immediately began recording six-second video clips at a mind-reeling rate. By some estimates, around five new Vines were being tweeted every second of the day [source: MediaBistro].

So what exactly are people sharing via Vine, anyway? Well, because of the short duration of the videos, Vine creators have to get their concepts across immediately. To that end, Vines tend to be fast-paced and mostly comedic (and more often, pointless and boring). As with all new communications channels, though, some marketing teams are producing slick ads hoping that they'll go viral via Vine.

But understand that in general, people aren't out to make art or ads via Vine -- they want to make you giggle. In a lot of cases, they succeed. Perform an Internet search for a Vine compilation and you'll find numerous, minutes-long collections of Vine clips all strung together. The end result is often hilarious and so fast-paced that your eyes hurt afterward.

Vines are pretty much what you'd expect. They include cute babies, silly pets and even sillier people. There are scripted fight scenes, car crashes, songs, pornography, art projects and of course, cats.

For the moment, Vine is spreading like an invasive weed across every fencepost of the Internet. Keep reading to see how to grow your own collection of Vines.