Biz Stone: Co-founder of Twitter. He's been "developing large-scale systems that facilitate the open exchange of information for more than a decade." Ahmir "?uestlove" Thompson: He updates followers on the musical and the mundane. With 1.5 million followers, he's a formidable presence on Twitter, helping new artists by posting clips of their rehearsals on "Late Night With Jimmy Fallon," where he and Grammy Award winners the Roots churn nightly as the show's house band. In a conversation that covers everything from privacy to the jaws of life to Prince possibly lurking on Twitter, the Dirty Projectors and "paying attention to what the users need," these two trendsetters get down to the Twitter nitty-gritty.

Did you expect Twitter to have such an impact on the way artists communicate with fans?

Stone: I was pleasantly surprised . . . to find out that folks like ?uest, who adopted Twitter really early, were using it to communicate with fans. It was the best possible scenario because they were actually listening to fans. And even cooler was that they were communicating with other artists. It was exactly what I thought wouldn't happen, which was this very open conversation.

How did you first become aware of Twitter?

?uestlove: On the cover of Philadelphia magazine; the story was "you don't know this woman, but 100,000 people follow her." She used Twitter to draw attention to her fashion blog. I looked up Twitter. When you first join, it's jokey and you do stupid stuff. But I got to 100,000 followers quickly and I was like, "Whoa, this could be a promotional tool." I realized that I could use Twitter to finally cut down that velvet rope or fourth wall that so-called entertainers are supposed to have. I decided I was going to use the account to show people how "normal" the life I lead actually is. It's a contradiction, because you can't be "normal" and talk about going to Madonna's Oscar party. But I was tweeting from the ambulance when our bus turned over in Paris. They were getting the jaws of life and I was like, "I need to tweet this." To show people real situations.

Stone: It does break down that fourth wall, but then once in a while we get vicariously into Madonna's party. You may be following ?uest, but you're also following your mom, your buddies.

?uestlove: I wish you guys would invent a device where you could prevent someone from lurking on your feed. My mom spends about four hours on my Twitter a day. At 11:00 p.m. she's like, "Ahmir, exactly how do you know Sasha Grey?"

Stone: We have to invent a mom filter.

In all seriousness, is a filter something you'd consider?

Stone: One of the things we've done from the beginning is keep it real black and white what's public and what's private. You're either all out there in public, or you protect your account, which means the only people who see your tweets are those who you allow one by one. It may have some disadvantages, in that there's one or two people you wish weren't looking at your tweets. But the overall benefit of being public and reaching so many people outweighs the one or two people you wish you could reverse parental-block. On the flip side, you can block people on Twitter who you don't want to hear from.

Any features you'd like to request from Biz?

?uestlove: I don't know how many artists have stalked me because they think I have some power to verify their accounts. Is there some sort of secret jury who decides who gets verified?

Stone: We've stopped accepting requests for verification through the website. We introduced verification because there were certain politicians and celebrities who were getting impersonated. Rather than chase down every fake account, we verified the one real account. But once you introduce a badge, everybody wants a badge. Regular folks, like some of our investors, were like, "Can you verify me?" But no one's going to impersonate them.

?uestlove: Whose idea was it to limit it to 140 characters?

Stone: Constraint really does inspire creativity. The reason we chose 140 characters though, is because we started out wanting to build on the mobile texting system. It had to work within the international limit of text messaging, which is 160, and we needed to leave room for the name of the author of the tweet. We wanted the tweet to be able to be read in its entirety across every single device. We had to play to the lowest common denominator, and that's SMS.

Is Twitter for all artists, or just those with the knack?

?uestlove: I don't have handlers. I know most artist accounts have their handlers [tweeting] . . . So I wouldn't recommend doing my level of tweeting. Two or three of my tweets have gotten me in major trouble and I avoided some major repercussions. But for the very basic ABCs of it, I think all artists should be on it. Like Prince, he's on Twitter, but he lurks. He's under an alias and will never officially use his Twitter account to benefit him. Which is really strange.

Stone: One of the things we've been telling folks who are not necessarily gung-ho about taking the baton and running with it, is to do just that. Think of Twitter as an information source that you can go to, to read about what people are saying about your album or your product. That ends up oftentimes with the person wanting to eventually use Twitter to say something. That, for us, is a better way to get people interested in Twitter-rather than saying, "You should tweet," right off the bat.

?uestlove: Twitter is the modern-day Paul Revere. Its ripple effect is faster and more effective than almost any type of ad. In the early '90s there were certain tastemakers you could entrust to promote your product. Twitter allows the artist to be his own tastemaker.

I learned about Esperanza Spalding on Twitter. The same with Odd Future. The Dirty Projectors are another great example of how Twitter has changed someone's course overnight. On a whim, I took my Flip cam when they performed, and put a 40-second clip on Twitter. The next day I woke up and every blog from Pitchfork to whatever had that clip on.

Stone: That's what's going on across all of Twitter. At least 25% of all tweets have a link in them, and a lot of times that link is to a piece of music or a videoclip. When we notice that behavior, we start doing stuff. One of the things we did recently was an integration with Apple's social network service Ping, so that if you're listening to a song on iTunes, you can just hit the tweet button and you can share it with all your followers and get taken back into iTunes to buy it. There's another service called Rdio, and you can listen to the whole song if you're both Rdio subscribers.

Does Twitter have the responsibility to help users provide more context to their tweets?

Stone: Not everybody reads the terms of service when they sign up to a website. But if you look at ours, I helped write them. They're written in a very conversational tone, and anything that sounds lawyerish has a yellow box explaining what it means. Basically, it says once you send out a tweet, it goes everywhere. It goes on people's mobile phones, it goes on CNN. It goes everywhere. That's going to be on you. So if you don't like the sound of this, then don't use the service.

We have a responsibility that people understand it's a public medium. People are still learning what works, what doesn't. Can you pull off humor in 140 characters? Will people get the joke? My example is, if I tweet I'm at a restaurant, I've got to assume it's an invitation for anyone around to join me. So I wait until I leave. Those are the subtleties that society in general is learning to understand when it comes to the new transparent way that we go about our lives and communicating. There's a lot of value in openness, but we also have to learn how to temper that. Occasionally we're going to get burned, but that's how we learn.

?uestlove: Do you ever fear the idea that you might become the next Friendster?

Stone: The fear is not about someone else. The folks most likely to bring us down are ourselves. One of the things we lived through, which was terrible, was that we weren't able to keep up with growth throughout 2008 and 2009. We had a lot of downtime. That's the kind of stuff that ultimately will make you fail. We had a small team then-like, 50 employees-and we're past 350 now. We're finally able to get to that point where we're not shooting ourselves in the foot every day. When we worry, we worry about executing on our plans.

There are others that are doing similar work, and that's a good thing for society in general; to have a variety of people working on a variety of cool tools that allow people to express themselves. But the thing that's most important is that we do our job and support the growth. That's what brings a service down-not paying attention to what the users need and not running a quality service. For example, focusing on money too early as opposed to features and growth.

?uestlove: Will we ever be able to add a comment to a retweet?

Stone: That's part of a larger initiative. One hundred and forty characters is the basic mechanism that carries a tweet through the system. But there's all kinds of meta information that can be added that gets carried along with it. For example, is the tweet referencing a song? Should the song be displayed? There's a world down the line-we're not working on it this second-there's a lot of associated content with that very simple tweet . . . something you're using to read the tweets can unpack a world of information.