Kony 2012 is a perfect example of this.
The plight of the child soldiers from Uganda in this video really resonated with the internet community, and the world at large, mainly because it told a story, and asked something very simple of it's audience: SHARE.
Spread the message, pass it on - very powerful, connection-building actions that build relationships between us, and can change the world.
As always, the real story behind Kony 2012 is a lot more complicated than it first appears on this documentary.
But I'm not here to cast a judgement on the film's validity. Regardless of that, it has made millions of people aware of who Joseph Kony is, and has made headline news.
The one thing we need to be aware of with virality is that truth is not necessarily at the centre of every great story, or documentary. You need to remain sharp online, and not fall pray to sharing content that has bypassed your critical faculties.