Launching and commissioning are two milestones in the construction of a Navy ship.

A ship is launched when it is first put into the water. At this time the ship is incomplete, and still requires considerable work to complete it and make it ready for service. When the ship is fully ready for use by the Navy, it runs acceptance trials to see if it will perform according to specifications. When this has been done to the Navy's satisfaction, and any discrepancies have been set right, the Navy's representative signs a paper officially accepting it from the builder.

By this time the prospective commanding officer and crew are on hand, and they then place the ship in commission. In a formal ceremony, the commanding officer reads his orders and assumes command, the colors are hoisted, and the ship then begins to function as a Navy command in its own right. The Navy's use of the word "commission" means the placing of a ship in active service.

The Navy does not refer to ships as having a "birth date." The date of first commissioning marks the beginning of a ship's active service, which is ended by its final decommissioning. The date of acceptance is simply called that; it has no special title.Launching and commissioning are two milestones in the construction of a Navy ship.