The popularity of Instagram spread like wildfire as more and more mobile phone users adapted smartphones with better cameras.

Since its debut back in 2010, Instagram has grown by leaps and bounds, going from start-up photography app to part of the biggest social network in the world.

Shocking then that it took until this week for Instagram to announce it hit the 100 million user mark, when you consider just how many millions of smartphones and Facebook users there are in the wild.

Still, it's an impressive milestone for a service jokingly known for its photos of cats in various states of annoyance and stills of food ready to be eaten.

Look at this Instagram

Interestingly enough, Instagram wouldn't be where it was today without the inclusion of the Android consumer base.

Prior to launching for Android in April 2012, Instagram was only able to cultivate around 30 million users from the iOS market.

Fast-forward 10 months, and you can see just how much of an impact broadening its horizons had on Instagram's success.

Despite the outcry and threats to leave the app from users worried that joining forces with Facebook would somehow impact the service, that vocal minority didn't affect Instagram's growth much if at all.

The launch of the browser version of Instagram earlier this month has only helped more people discover what's possible with smartphone photography, and there's no telling how much more the app will grow over the next two years with the growing adoption rates of smartphones.