If the mystic letters "NCC" mean nothing to you, be advised that the following information pertains to Star Trek, is not considered "official" by the producers of the show, and has no meaning in Real Life. It is noded purely for the entertainment of the Treknologists and other weird people who consider stuff like this "interesting".
The NCC-part stands for "Navigational Contact Code" or "Naval Construction Contract", depending on context. The following numbers indicate a type of serial number for the ship in question. For example, U.S.S Reliant has a registry of NCC-1864. This would indicate that the Reliant was the 1864th ship built by the Federation. This is not the case, however, as the numbers are not always assigned sequentially.
For the purposes of categorizing the ships, Starfleet uses a different scheme. The NCC-portion is replaced by other letters indicating the ship's type. The Following categorization is used in 2292:
Cruisers:
Frigates:
- FH - Heavy Frigate
- FR - Frigate
- FF - Fast Frigate
- FS - Small Frigate
Destroyers:
- DH - Heavy Destroyer
- DD - Destroyer
Scouts:
- SS - Superscout
- ST - Scout
Patrol Combatants:
Specialized:
- SC - Shuttlecarrier
- SO - Space Control Ship
Support Ships:
Other:
For example, the Federation-class Dreadnought U.S.S Entente, NCC-2120 would be marked as DN-2120.