TikTok CEO Shou Zi Chew at the offices of ByteDance, the Chinese owner of TikTok, in Shanghai on Jan. 25.  (Ore Huiying / The New York Times)

TikTok CEO Shou Zi Chew: 3 things to know

TikTok's CEO was relatively unknown to the U.S. public before Thursday, when he testified before a congressional committee concerned about data protections on the popular...