A subrace represents a branch of a race, typically one that exhibits slight differences in appearance, outlook, and adaptation compared to other members of the race. The implementation of these in Neverwinter Nights is left open to the community. The differences in appearance can usually be achieved by a player during character creation, while differences in outlook can be roleplayed. Differences in adaptation often means a different set of racial modifiers or racial feats, and these will only be effective if specifically implemented by a module. (Of the BioWare releases, only the premium module Witch's Wake implements subraces.)
A subrace is selected during character creation by clicking "Subrace" after selecting the base race, then entering the name of the subrace in the provided field. If subraces are not explicitly supported by a module (as is the case with the official campaigns), the effect of this field is to change what is displayed as the race on the character sheet and what might be spoken by various non-player characters when they refer to a character's race. On the other hand, if a module does support subraces, and if the entered subrace matches one the module supports, then changes may be made to the player character when the module starts to represent that subrace's adaptations. (Typically, these changes do not apply during level-up and do contribute to the various caps enforced by the game. They are typically lost when starting a new module in multiplayer mode if either enforce legal characters or item level restrictions is turned on, but might be kept otherwise, particularly if the new module does not itself support subraces.)
When entering a subrace, any strictures set by the module must be followed. For example, if a module accepts "Drow Elf", then it is possible that the module will accept neither "Drow" nor "Elf, Drow" nor even "drow elf". Some modules have looser requirements and are more accepting of variances — especially with the introduction of
SetSubRace() in patch 1.31 — but what is entered still must exactly match what the module requires in order for the subrace to take effect.