In Pictures: Facebook turns 10 - A look back at th...
The birth of the “Like” button
In early February 2009, roughly five years after the site was created, Facebook introduced the "Like" button, allowing users to express when they liked their friends' posts or photos without having to post a comment. It was hardly the first iteration of the "like" concept on a social site, but it's since become an integral part of Facebook.
In Pictures: Facebook turns 10 - A look back at the milestones