Nicholas Carlson chronicles the four-year journey of Pinterest, including how they failed at a mobile app and then created a web app for putting photos into "buckets":

Pinterest was started four years ago, right as the recession was really getting underway; in 2008. It had a different name and a different CEO, then. It had three cofounders. Two of them are no longer around. A third "cofounder" joined just last year.

The truth is just as one source close to a Pinterest investor told us: "Pinterest is an overnight success four years in the making." Here's that story.

Pinterest started life as a mobile shopping mall app called Tote, released in early 2009.

The pivot from mobile app Tote to the new Web-based product "was a very progressive iteration," not an "epiphany" says a source close to early employees:

When Cold Brew Labs decided to bench Tote and launch Pinterest in late 2009, the company was not expecting the site "to be one of the top 15 properties on the Web in two years," a source close to investors tells us.

"There wasn't any grand vision."

This is good, because when Silbermann and Sciarra showed off Pinterest to their friends and family at the end of 2009 and the beginning of 2010, their friends and family responded with a resounding: "Huh?"

"No one got it," says Silbermann.

In early 2010, their first investor (First Mark Capital in New York in early 2009) pushed a certain New York-based magazine publishing company to invite the Pinterest founders to pitch them. Investors dared to hope for a sale, but the magazine publishing company resisted taking the meeting. The Pinterest founders pushed for the meeting anyway. The magazine company's corporate development people didn't really see the point in Pinterest and passed. Pinterest was an overnight success nobody saw coming.

So the founders left and tried to build Pinterest instead. They went through many design iterations.

Slowly over the course of a year they accumulated users.

By the end of 2010, Pinterest was growing 50 percent per month, but it still had under 100k users.

They didn't release an iPhone app till March 2011; at that point the mobile app and the web app helped each other grow.

In May 2011, they raised 10 on 40 from Bessemer and SV Angel.

By September 2011, growth had gone vertical. At that point, they had 8 employees. They raised 27 on 200 from Jeff Jordan at a16z thanks to an intro from angel investor (and Eventbrite founder) Kevin Hartz.

One of the co-founders Paul Sciarra fell deep into anxiety, and in March 2012 he left the company.

Pinterest now has 30 employees.

No one in Silicon Valley understood Pinterest until it was already successful: http://pandawhale.com/convo/567/no-one-in-silicon-valley-understood-pinterest-until-it-was-already-successful