Bump mapping is a 3-D graphics simulation technique that uses object lighting calculations to alter texture map surface bumps without additional polygons. Bump mapping is an extension of Phong shading and the Phong reflection model.
Bump mapping is used by multiple programs and applications, including gaming, astrophysics, architecture, biology, chemistry and biology.
Bump mapping should not be confused with texture mapping.
Techopedia explains Bump Mapping
Bump mapping requires heavy processing resources and is usually hardware driven. Bump mapping calculation support is specified by 3-D graphics card chips. Bump mapping adds surface detail by responding to light direction.
Two popular bump mapping types are:
Emboss bump mapping: A multipass algorithm technique that extends texture embossing and duplicates texture images. The images are then shifted to the desired bump amount, underlying texture is darkened and excess texture is trimmed. Finally, the duplicate texture images are combined as one. Emboss bump mapping is also known as two-pass emboss bump mapping.
Environment mapped bump mapping (EMBM): A surface detailing method that incorporates texture/bump/environment maps. Bump and environment maps combine after the shifted environment map is applied to the texture map.