Vine co-founder Dom Hofmann has always been a film nerd. He spent summers as a kid making movies, but had more fun shooting than editing. His interest dropped off, but filmmaking lingered in the back of his mind. Nearly two decades later, Hofmann's iPhone camera roll is a dense grid of video clips, not photos. He built an app called Vine to satiate his desire to create short films, which now has its own Tribeca Film Festival category and holds the number one spot in the US iTunes App Store. The app began with the idea of cuts — the "atomic unit" of film, as Hofmann says — but grew into something bigger thanks to a single mantra: "Great apps are simple and complex."

"Great apps are simple and complex."

"Every single part of what we did in Vine was informed by this notion," he said last night at the NYC Apps meetup, a small networking event for developers and designers. He then rattled off the names of a few other apps that subscribe to the same principle. "Dark Sky solves the simple problem of 'Do I need to bring an umbrella?' Behind solving that simple problem is a complex set of algorithms," he said. Cut the Rope, on the other hand, increases in complexity but never asks you to do anything besides cut a rope.

"These apps are tackling complex problems in simple ways," Hofmann said, and in his mind, this principle is the secret to Vine's success. "The barrier to disregard an app is much lower than it's ever been," he said. "You need to make clear what you're doing within a couple of minutes or people are going to forget about it forever."

So why does this formula work? Steve Jobs and Jony Ive have always defined simplicity as stripping away complexity, but Hofmann thinks a wholehearted devotion to that approach isn't the answer. "We don't really think it's about reducing complexity," he said. "We think it's about concealing complexity." Vine takes a variety of nearly invisible measures to deliver a simple filmmaking experience to users. For example, the app encodes video as you record it, so by the time you're done shooting, the app's finished processing it. Also, audio between shots is gently crossfaded to avoid abrasive sounds and pops during the transitions.

"We don't really think it's about reducing complexity. We think it's about concealing complexity."

The Vine team had a good grasp of how to simplify the act of filmmaking, but something was missing. An early version of Vine let users shoot video, at which point the app dumped the clip into the user's camera roll. "We gave that to people and they would SMS us their videos," Hofmann said. "We thought gosh, we should do a social layer." The first step would be learning how to embed Vine clips inside Twitter's new Cards platform. The company met with Twitter to learn the ropes, but techspeak soon evolved into acquisition talks. Twitter hopes Vine will become the de facto means of sharing short video clips on the web, much as Twitter is the gold standard for sharing short thoughts and sentiments. It's working well so far, with people like Barack Obama using Vine to upload their latest White House videos.

Vine says an Android app is coming "soon," and a feature to let you tag friends is already awaiting approval from Apple. In the meantime, the company remains focused on concealing complexity, and ensuring a simple, painless experience for users. Take the feature Hofmann and his team built early on when they discovered that the final moments of many clips felt awkward and cut-short, even when testers were provided with 10 seconds to work with. "It wasn't an issue of length. It was people having a hard time gauging [how much time] they had left based on the progress bar," Hofmann said, "so [today] we let you shoot past the 6 seconds up to 6.5 seconds." In other words, the app can continue recording up to half a second after the progress bar ends.

If you have a look in your camera roll, you might notice that each video's timecode reads 7 seconds instead of 6. The quality of the "final cut" in each Vine video instantly went up by 10x, according to Hofmann. "It's another case where we had to take something complex — how do I figure out what I've got left? — and make it simpler," he said.