Ship commissioning is one of the ceremonial and administrative steps in the process of taking a vessel, especially a warship, from concept to service. It follows a number of steps, including the financial authorization, ship design, and the sometimes ceremonial first step of laying the keel. A keel is the bottom structural member of many hull types, and, in a modern vessel, can be a massive piece of metal. The symbolic start may be simply to place a block of metal, or perhaps to make a small weld.
Commissioning is the ceremony by which the ship is taken into the navy, although it is by no means ready for service. At the time of christening, the major structural components are usually present; the ship looks like a ship. The traditional christening ceremony involves a distinguished person, usually with some association to the name of the ship, smashing a bottle of champagne on the bow and saying "I christen thee (name)". Nevertheless, a newly commissioned warship is usually still in drydock, and lacks many of its critical systems such as weapons and electronics. Above all, it lacks its crew.
Launching is the next major symbolic step, although much still needs to be done; the most basic question that can be answered only at this point is whether the ship is watertight. Small leaks are likely. Some major hull penetrations may still need to be made or adjusted.
Launching and commissioning are not always in that order. In any event, once the ship is launched, it will need to undergo builders' trials before it is accepted on a practical basis. Once builders' trials are complete, the navy begins its trials, sometimes with a "precommissioning" crew and sometimes with the "plank owner" or initial crew.
A major modern warship can take many years between its first steps and becoming operational. In demonstrations, some mass-produced Liberty Ship transports of the Second World War were ready in days. Indeed, the complexity of some modern warships is such that the class may be cancelled or reduced before full construction; some individual first ships of a class have been cancelled, variously because the need no longer existed (e.g., a war ended), their technology was obsolete, or they were no longer politically or financially affordable.