Prestige classes are classes that have requirements (other than alignment restrictions) that must be met before a player character can gain levels in the class, as opposed to character classes, which are open to all player characters of allowed alignments. These powerful classes grant characters unique new abilities unavailable to the base classes. A prestige class cannot be chosen for a starting character; it must be earned through careful advancement. For example, some classes require a certain number of ranks in one or more skills, while others require the ability to cast arcane spells. The requirements for each prestige class are listed in the article for that class.
Prestige classes are limited to 10 class levels through character level 20. Starting with character level 21, prestige classes can advance beyond level 10 (at which point they are considered epic) with no further limitations.
In Neverwinter Nights Edit
All but one of the prestige classes implemented in Neverwinter Nights were provided by the expansion packs, and are among the few things that may require the first expansion pack specifically. (Most other additions — such as skills and spells — from the first expansion pack were also included in the second.)
The prestige classes that are available (only) if Shadows of Undrentide is installed are:
The prestige classes that are available (only) if Hordes of the Underdark is installed are:
The prestige class, was made available in patch 1.69 and is available regardless of which expansions are installed.
NWN Enhanced Has made available six more prestige classes(all patches and expansions must be installed).