Instagram is one of the most popular apps available for both iPhones and Androids today. This photography app is essentially a photo-sharing network that enables users to share their photos with friends, and also browse the pictures of everyone they "follow".

This free app was recently purchased by Facebook for an astounding one billion dollar price tag! The app also allows you to easily share your pictures on other social media sites like Facebook and Twitter, so that you can share them all over the web!

Perhaps the most unique thing about the app, however, is all the unique filters and treatments you can apply to your photos to enhance them, and even give them a vintage look. Plus, you can always recognize an Instagram photo by its iconic square layout.