Lars Backstrom is a Data Scientist at Facebook, where he works on data analysis and machine learning systems. Since joining Facebook, he has made significant improvements to the friend suggestion ranking system. He is responsible for the backend system which does feature extraction and ranking of the friends of friends of over 500 million users (times an average of 40,000 friends of friends means 20 trillion rankings). Before joining Facebook in 2009, Lars was a Ph.D. student at Cornell University, where he developed algorithms for data mining in social networks, query logs, and server logs.