Tricia Wang may hold the record for most Instagram photos taken on Chinese trains. A sociologist, ethnographer, and corporate consultant who studies global technology use among migrants, low-income people, youth, and others on society’s fringes, Wang has worked for the past several years in China. Since 2005, she’s crisscrossed the country--often riding the rails--observing the impact of digital technology on the lives of rural workers migrating into the cities, and more recently, documenting the wildfire spread of new social-media platforms like Weibo and Renren. Recharging at her home base in Brooklyn after a year away, Wang spoke with Fast Company about her field of digital ethnography, the benefits of working outside of big institutions, and what U.S. tech entrepreneurs can learn from their peers in China.