Here's how different Instagram looked in 2011, and how it's changed over time

In April 2012, as Facebook was making its way toward an IPO, Mark Zuckerberg shelled out $1 billion to buy Instagram, a 13-person startup with a hot photo-sharing app.

Instagram was just two years old, had zero revenue, and needless to say, some people thought Zuckerberg was crazy at the time. But that acquisition could turn out to be one of Zuckerberg's best decisions.

Instagram now has 500 million monthly active users, and continues to grow, especially internationally. It's also in the process of a serious makeover: Instagram recently overhauled its icon and the app's color scheme, and will transition its feed from a chronological one to an algorithmic one (like Facebook).

But it's not the first time Instagram has switched up its look. Instagram's interface from 2011 looks a bit goofy today.

Great Apps Timeline is a website that tracks how popular apps like Uber or WhatsApp have changed over the years. They put together a walkthrough of how Instagram's look has evolved over time.

Here it is, from 2011 to 2016: