Kevin Systrom was asked on Quora how Instagram started and here’s the response:
First off, we have to say that we never expected the overwhelming response that we’ve seen. We went from literally a handful of users to the #1 free photography app in a matter of hours. But as my cofounder likes to say, Instagram is an app that only took 8 weeks to build and ship, but was a product of over a year of work.
The story starts when I worked at Nextstop. While I was there working in marketing, I started doing more and more engineering at night on simple ideas that helped me learn how to program (I don’t have any formal CS degree or training). One of these ideas was combining elements of(check-ins) with elements of Mafia Wars (hence the name Burbn). I figured I could build a prototype of the idea in HTML5 and get it to some friends. Those friends ended up using the prototype without any branding elements or design at all. I spent weekends working on improving the prototype for my friends. At a party for the Hunch folks I ran into a bunch of people who would basically make starting Burbn a reality. At that party were two people from Baseline Ventures and Andreessen Horowitz. I showed the prototype, and we decided we’d meet up for coffee to talk about it. After the first meeting, I decided to take the dive and leave my job to go solo and see if Burbn could be a company. Within two weeks of leaving, I raised $500k from both Baseline and Andreessen Horowitz, and started work on finding a team.
Mike Krieger and I started talking and he decided he liked the idea of helping start the company. Once he joined, we took a step back and looked at the product as it stood. By this time, we had built Burbn into a (private) really neat HTML5 mobile web app that let you: Check in to locations, Make plans (future check-ins), Earn points for hanging out with friends, post pictures, and much more.
We decided that if we were going to build a company, we wanted to focus on being really good at one thing. We saw mobile photos as an awesome opportunity to try out some new ideas. We spent 1 week prototyping a version that focused solely on photos. It was pretty awful. So we went back to creating a native version of Burbn. We actually got an entire version of Burbn done as an iPhone app, but it felt cluttered, and overrun with features. It was really difficult to decide to start from scratch, but we went out on a limb, and basically cut everything in the Burbn app except for its photo, comment, and like capabilities. What remained was Instagram. (We renamed because we felt it better captured what you were doing — an instant telegram of sorts. It also sounded camera-y)
So 8 weeks later, we gave it to our friends, beta tested, bug fixed, etc. and this Monday we decided it was ready to ship. We’ve got a long road ahead of us, but we’re encouraged by the adoption and usage that has far exceeded our bets pre-launch.