Commissioned after the events of the whale-probe crisis, the Enterprise-A was Kirk's ship for his final missions.
The USS Enterprise-A was the successor to the original Enterprise, a refitted Constitution-class starship given to Captain Kirk and his crew after the loss of the first ship. She was presented to the crew in recognition of their heroic act in saving Earth from a probe, and she was seen as a gift from a grateful Federation.
The ship was initially problematic, with many of its systems still not fully functional, but the crew worked to get her into shape. She took part in several major events, including a mission to rescue hostages on Nimbus III, where Kirk's crew met Sybok and faced the legend of a hidden paradise, and the diplomatic crisis that followed the destruction of a Klingon moon. In the course of those events the crew helped to prevent a conspiracy and set the stage for peace with the Klingons.
The Enterprise-A was commanded by Kirk until the crew retired. Her service ended with the end of the original crew's adventures, and she was decommissioned at the end of the sixth film, where the crew signed off with a final log entry.