In a starship or space station context, a crew operated and maintained a starship or space station to the best possible standard to complete the missions assigned. The crew were divided into sections and then further subsections within those sections to work on specialized tasks. In Starfleet, three major divisions in the 24th century were the command division, the operations division, and the sciences division.
The commanding officer usually headed the crew, followed by the senior officers. There was a chain of command, determined by rank and being an officer or crewman. The entire crew were sometimes referred to as crewmembers.