In most organizations, the general manager has final say in terms of roster decisions (e.g. trades, free-agent signings) and coaching/front office personnel (e.g. hiring, firing, promotions, reassignments). In organizations that employ a president of baseball operations, the general manager is considered second in command. Not every club employs a president of baseball operations, though some examples include the 2016 Cubs (Theo Epstein), '16 Dodgers (Andrew Friedman) and '16 Indians (Chris Antonetti).
General managers have a number of assistants, as well as scouts and statistical analysts, working underneath them. Additionally, general managers also act as a face of a franchise in terms of speaking to the media and making public appearances.