Jack Dorsey: I have maps.
Lara Logan: And trains.
Jack Dorsey: Yeah.
Studying trains was the beginning of his life-long obsession to learn how things work in the real world and translating that into the virtual world. Young Jack was intrigued by the messages he heard coming out of the St. Louis emergency dispatch center. At home he listened to it all on a police scanner. And he was struck by the fact that everyone talked in short bursts of sound - a system of communication that later inspired him to invent Twitter.
Jack Dorsey: They're always talking about where they're going, what they're doing and where they currently are. And that is where the idea for Twitter came was now we all have these cell phones. We had text messaging. And suddenly we could update where I was, what I'm doing, where I'm going, how I feel. And then it would go out to the entire world.
As a teenager, he created software that tracked the movement of emergency vehicles on a map. Then he tried to get a job with a large dispatch company in New York but there was no contact information on their website.
Jack Dorsey: I found a way into the website. I found a hole. I found a security hole.
Lara Logan: Is that-- are you-- is that the same thing as hacking?
Jack Dorsey: It's-- ha-- yes. Hacking-- hacking is-- hacking is-- is--
Lara Logan: A crime.
Jack Dorsey: Well, no. Criminal hacking is a crime. Hacking is actually a--
Lara Logan: Hacking for a job application is not a crime?
Jack Dorsey: No, no, no, no, no. No, not a crime at all. And I emailed them and I said, "You have a security hole. Here's how to fix it. And I write dispatch software." And--
Lara Logan: And they hired you.
Jack Dorsey: And they hired me a week later. And it was a dream come true, which is a weird dream for a kid.
Now the kid who ventured to New York when he was 19 has a new dream -- to expand Square globally. He's moved into Canada and Japan and opened an Internet shopping site. Dorsey knows he'll have some stiff competition.
Lara Logan: PayPal is a competitor of yours. It has a similar system. Google, Walmart and Target are developing their own systems. What prevents the competition from putting you out of business?
Jack Dorsey: Well, you know, our take on this is you can worry about the competition, you can constantly look in your rearview mirror and you can constantly look around and really not notice the road ahead of you. Or you can focus on what's ahead of you and drive, and drive fast, right? And drive within the speed limit, of course, but drive fast.
Lara Logan: But hopefully faster than everyone else.