Launched in 2004, Flickr was around for over a year before Facebook decided to allow its users to upload more than just a basic profile photo. It had plenty of time to become the go-to photo service. And in many ways it has succeeded -- but it still can't keep up with Facebook. Photos, for everybody except the most professional of photographs (and even some of them, too), are naturally social; they lend themselves to a network of friends and acquaintances. It's not about light and shadow and framing and composition; it's about capturing a moment.

Facebook knew that. By the end of this summer, Facebook expects that it will be hosting more than 100 billion photos, several times what you can find on Flickr. Users are uploading millions of photos every few minutes. How did we reach this point? In the infographic embedded below, Pixable looks at the history and evolution of Facebook photos, including some of the legal and ethical controversies surrounding the popular feature.

Infographics are always a bit of a hodgepodge of statistics culled from a variety of sources. Here, we sort through the clutter and pull out some of our favorite facts and figures:

• Facebook added the photo application in October 2005, making it the first photo site with an unlimited quota for uploads. In 2007, Facebook took the lead for the greatest number of monthly visitors to a photo site with 23.9 million. By 2008, the social network was hosted 10 billion photos. The following year, 2.7 million photos were uploaded to Facebook every 20 minutes.
• In February 2009, the Like button was introduced on Facebook's photo feature. In October 2010, Facebook added a download button and photo organization tools, including drag and drop. In February 2011, two years after the Like button was introduction, Facebook started to display photos on a black pop-up background.
  

Check out more Infographics on the Technology Channel.