The author thanks Catherine Tucker, Nikhil Agarwal, and Dean Eckles for guidance and support on this project and Sinan Aral, Sarah Bana, Seth Benzell, Rahul Bhui, Avinash Collis, Tim Di Silva, Glenn Ellison, David Holtz, John Horton, Madhav Kumar, Jia Liu, Carlos Molina, David Rand, Manish Raghavan, Mohammad Rahman, Tobias Salz, Ananya Sen, Lena Song, Sebastian Steffen, Duncan Simester, Hong-Yi Tu Ye, Emma van Inwegen, MacKenzie Walker, Birger Wernerfelt, Michael Zhao, and numerous seminar participants for helpful conversations, comments, and suggestions.