Electing the Speaker of the House of Representatives: Frequently Asked Questions [Updated November 24, 2020] [open pdf - 818KB]
From the Summary: "This report briefly poses and answers several 'frequently asked questions' in relation to the floor proceedings used to elect a Speaker of the House. Current practice for electing a Speaker, either at the start of a Congress or in the event of a vacancy (e.g., death or resignation), is by roll-call vote, during which Members state aloud the name of their preferred candidate. Members may vote for any individual. If no candidate receives a majority of votes cast, balloting continues; in subsequent ballots, Members may still vote for any individual."
CRS Report for Congress, R44243
Congressional Research Service: https://crsreports.congress.gov/