Factbox - Five things to watch as Facebook, Google, Twitter CEOs testify in Congress

FILE PHOTO: Facebook, Google and Twitter logos are seen in this combination photo from Reuters files. REUTERS/File Photos/File Photo

WASHINGTON (Reuters) - The CEOs of Facebook, Google parent Alphabet, and Twitter testify before Congress on Thursday for the first time since pro-Trump supporters stormed the U.S. Capitol, an attack in which critics say social media played a crucial role.

Here are five things to watch for in the testimony of Facebook Inc's Mark Zuckerberg, Sundar Pichai of Alphabet Inc and Twitter Inc's Jack Dorsey before two subcommittees of the Energy and Commerce Committee: