A texture pack is a collection of resources, designed to change and enhance the look and feel of a WAD. Texture packs contain, for example, a SWITCHES lump to define new texture pairs or an ANIMATED lump to define new animations. Textures are crafted for patches, but also for flats and skies. Larger packs will also include resources to change the PLAYPAL or to modify the COLORMAP. Texture packs are usually stored in the form of a PWAD.
When the Doom source code was released, much of the focus was spent on crafting new mapsets using the existing textures that Doom had available. With DeHackEd a new and easier way to add new monsters, often with new sprites, was made available. The next step was to add custom textures to complement these new monsters. The GothicTX texture pack was one of the first packs to popularize the concept.
In later years, texture packs were more often released, usually as a resource to help mappers with the creations of their levels, usually with larger projects like megawads. The Community Chest series became highly popular through the inclusion of their own custom texture packs, often being used outside their original intentions.
List of texture packs