Jack Dorsey was born on 9 November 1976 in Fairmont City, Illinois. He attended the Missouri University of Science and Technology before transferring to New York University.  

He dropped out of university and left his job as a programmer at a taxi and courier dispatch service, an interest he had since the age of 14, to move to San Francisco. The following year he set up a similar business that would dispatch couriers and emergency services from the web. It was during this time Jack had the idea of a real-time short message communication service inspired by AOL Instant Messenger and LiveJournal that would allow users to give live updates as to where they were and what they were doing. 

Following several failed attempts, a project code named twttr began after Jack’s employer Odeo had a brainstorming session about the idea. Odeo employees used the first prototype as an internal communication service, however a full public version known as Twitter was introduced on 15 July 2006. "We came across the word 'twitter', and it was just perfect," said Jack. "The definition was 'a short burst of inconsequential information,' and 'chirps from birds'. And that's exactly what the product was."

In October that year alongside Biz Stone, Evan Williams and other members of Odeo, Jack formed Obvious Corporation and bought his previous employer, which included all of its assets. Twitter then became its own company in April 2007.

Twitter gained huge notoriety at the South by Southwest Interactive (SXSWi) conference in 2007, where usage of the site grew from 20,000 tweets per day to 60,000. After winning the festival's Web Award prize, Jack and his colleagues said on stage "we'd like to thank you in 140 characters or less. And we just did!"

After a year of exponential growth, in 2008 it was announced that Jack would take a less active role in the business and stepped down from his role as CEO to become Twitter's Chairman of the Board.

The following year Jack announced the creation of a new company, preferring to tweet rather than issue a press release. “Announcing our new company, called @Square, which I’m thrilled to be a part of: http://squareup.com.”

Electronic payment service Square was established to enable credit card transactions through mobile phones. “For me personally, it goes back to three concepts of bringing immediacy, transparency and ap­proachability to industries and to social interactions,” cited Jack. The company was launched in May 2010. 

However within a year of inception it was revealed that Square was not compatible with the Apple iPhone 4, due to its problematic antenna. "This renders our card readers inactive for your iPhone 4," the company conceded. "We are working on redesigning our card readers and will be contacting our iPhone 4 users as soon as they are ready for shipment."

In May 2011, Jack said that a new Square service would enable retailers to replace their cash registers and credit card readers with iPads thanks to the company's mobile application. He went on to add that buying a cup of coffee would be "as easy as buying a song off iTunes. This makes the experience of buying and selling magic.”

In mid 2012, Square announced it was teaming up with world-renowned coffee store chain Starbucks, who would replace its transactions systems in the US with Jack’s smartphone technology. Commenting on the $25m deal, Jack said: "This is definitely a pioneering deal for us. It really validates the technology." In September, the company was valued at $3.25bn after it raised $200m in new funding. 

In October, even though Jack revealed he would be stepping back from day-to-day operations at Twitter to concentrate on Square, he asserted: "I’m fortunate in life to be a part of two foundational and mission-driven organisations, and I’m always going to fight like hell to make them thrive."

Over the course of 2012, Square processed $8bn in payments and its workforce had grown to more than 400.

Since 2012, Jack has dated model Lily Cole. The couple spent 2012 New Years Eve together on a yacht in in St Barts, which reportedly cost Jack $240,000 a week.

In June 2012 it was revealed that Jack paid $9.9m for a 3,734 square foot home on a cliffside above San Francisco Bay.

Before each working day, Jack runs three to five miles.

He remains a regular user on Twitter (@jack), posting various photos about his work and social life in San Francisco. He has also revealed his musical tastes range from The Beatles to Lauren Hill and likes to listen to audiobooks by Ernest Hemingway. 

On being forced to step down as CEO of Twitter:

"I was angry at the board. I was angry at my co-founders. I was angry at myself."

On 'users':

"The entire technology industry uses the word “user” to describe its customers. While it might be convenient, “users” is a rather passive and abstract word. No one wants to be thought of as a “user” (or “consumer” for that matter). I certainly don’t."

Jack has been tipped as the technology industry's next Steve Jobs and shares several characteristics with Apple's co-founder. Both started out as programmers and have been heralded as visionary's in their respective fields. Although Jack never got to meet Steve, he said: "I learned a lot from him, though, from afar."

Jack is a believer in teamwork and collaboration with Square's office a vast open space:

"We encourage people to stay out in the open because we believe in serendipity–and people walking by each other teaching new things," noted Jack.

Keith Robois, COO at Square, has said that Jack possesses the three qualities needed as a CEO-founder. He thinks strategically, drives design and drives technology:

"Some people who are really good at one can build a pretty foundational company," noted Keith. "Most people who are very successful are good at two. But Jack is the only person in the Valley I’ve met who’s all three. He’s a first-rate strategist, a first-rate designer, and a first-rate technologist."

Commenting on his weaknesses, Jack asserts:

"I do have a tendency to really think about things by myself and decide things. I can be silent at some times which unsettles people a bit, because they don't know what I'm thinking. The biggest thing I've learned is that I need to communicate more."

After receiving The Wall Street Journal's Innovator of the Year Award in 2012, Jack said:

"Every single one of us on this planet has an opportunity to make a positive impact in this world, and I’m proud and humbled by the millions of people who chose to use Twitter and Square daily to do exactly that."

1. How can you convince retailers that Square is a viable and more convenient payment system compared to traditional means?

2. Even though you have taken a step back from Twitter, are you confident that the company’s advertising strategy is heading in the right direction?

3. What lessons did you learn from your demotion at Twitter and how has this affected your role as CEO at Square?

Evan Williams, co-founder, Twitter:

Jack "took Twitter through an order of magnitude of growth and two major rounds of financing, while safely navigating some very rocky waters that would have taken even more experienced leaders down with the ship."

Biz Stone, co-founder, Twitter:

"It’s almost as if the whole of Square is a manifestation of Jack’s mind—everything has to be artisanal. He was always that way, but now he has the gravitas and authority to make it happen."

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