our zakari introduces us to four-square, leading in scientific innovation and encourages others to do the same. >> four square reportedly grew by 3,400% in 2010. its founders are dennis crowley and navin. so what is four square? >> so four square, what we're trying to do is build applications for mobile phones that help make the world easier to explore for people. and people use four square to check in all sorts of places. you can open you are four square pretty much anywhere you are in the world and it will give you tidbits of things you should be doing nearby, so you can check in at bars or coffee shops and when they check in, we let their friends know where they can find them. and if i want to check in at four square headquarters, i can find it on the list and broadcast that to all of my friends that i'm at four square headquarters with cnn. >> so if you were to -- if i