And that puts Foursquare smack in the middle of a swirling debate in Washington D.C. over privacy on the Internet and whether a law should be put in place to protect users.

  The firm, just four years old, has generated a ton of buzz  and has attracted investors including Twitter founder Jack Dorsey and Silicon Valley angel investor Ron Conway.

 The opportunities are huge: if you know a person’s location, then Radio Shack can push a deal from its store around the corner.

 Post Tech talked to Foursquare co-founder Naveen Selvadurai about privacy, the company’s explosive growth, and plans ahead.

Here’s an edited version of the chat:

Q: What’s your approach to privacy?

A: We always like to say that we would never build anything that we personally wouldn’t use ourselves. We also want users to have control in their interaction with the app. Users decide if they want to push to Twitter or Facebook, over what information they want to share and send.

 Q: Some government officials in Washington feel nervous about software that tells where a user is through location-based services.

A: We don’t passively track users, which is a misconception about Foursquare. We are a check-in service so a user has to actively check in to let people know where they are.

With any new features we present with commerce, users have to choose to participate.

There is a lot of misunderstanding about location based services. On Foursquare, if you don’t want to people to know you are on a date or with a friend at a certain place, then you don’t have to let people know. You don’t check in.

Q: Did you at any point do passive tracking, using GPS and other technology to constantly find location of users?

A: No. We never thought of this because early on we decided the service should be user generated and completely open.

Q: Do you have designated staff members in charge of privacy? Like a chief privacy officer like you see at other Web firms?

A: We don’t have someone appointed just for privacy, but we have people like our in-house counsel who think of these issues. The product is such that there are different arms to this things and a couple different heads in charge of those things so no one person is assigned [to privacy issues].

Q: Users have to be at least 13 to use the service. Do you think that there should be special privacy considerations for youth? For those users under 18?

A: We basically are very clear that you have to add friends into your Foursquare network before you share your location. It’s not like some applications where anyone can decide to follow you.

Q: But wait, when I checked into Dulles Airport the other day, I saw a bunch of strangers nearby me.

A: By default, you have all the actions to choose from. But users can also toggle through services they can opt in and out of.

Q: So no special considerations for youth?

A: This is very much user generated. Parents can be involved and can access privacy settings for their needs. If you only want your friends to see your history, you can adjust settings to that.

With a lot of these things, we will figure things out as we go along. We are still a younger service and most of the policies are trying to catch up with things people are doing. If users ask for a certain thing, we are likely to do that.  The more we learn from users about what is good and bad, and the more we learn about businesses and using platform the better we make the system.

 Q: Are you getting involved in discussion in Washington D.C. at the Federal Trade Commission or on Capitol Hill about privacy legislation and your views?

A: Not so much. We have a relationship with the city government here but we aren’t big enough to be in those conversations. We have 60 employees in New York and San Francisco. Even though there is a lot of buzz about location, we are still a baby.

Q: How is the mobile advertising industry growing?. It seems to be slow in the making.

A: We are building out that side of the business for sure. At the moment, we are focused on a great product for users and local businesses. If I go to a coffee shop four to five times a week, maybe I should get a reward, like a free cup of coffee. We want to play around with users and see how they are reacting to these things. Are these engaging experiences? Are these experiences leading to new users?

Q: Do you see Groupon and Living Social as competitors or partners?

A:  We complement each other. I was on a panel and we were talking with Groupon and I said one thing these sites do well is attracting new customers.What we are trying to do is getting new customers and building for loyalty. If you are loyal, maybe you will be a repeat customer, which builds brand loyalty. It’s almost like getting VIP service somewhere, like the first class lounge at the airport.

 Q: How much do you care about Internet privacy debates in Washington?

A: As a technologist who cares about the future of technology and the Internet, I don’t want people to misunderstand what they are applying rules to. We don’t want there to be a misunderstanding about technology adn apply ruels that lock it down. If you want to be secure, we have technology that can help. If you dont’ want to use a password, you can get a key ring. New standards are being published for “Http” traffic. “Https” is an example of a collaborative effort by technolgists of a standard for more security.

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