   Normal  & Bump Mapping ?
  What are these two mappings. and how different are they from each other and height maps ?. And For what purpose can they be use like height maps are for rendering terrains .. I guess thats abt it ... height map cant be use for other things thats what i think as the name suggests :P ... correct me if I m wrong ... so what abt these two mappings. .. Any good theortical tutorial abt them?.   
  Normal Maping is a type of Bump mapping and the most common type you see today. Normal Maping is applying a texture with a per pixel normal that you use to calculate the lighting of fragments. This lighting trick makes it appear likes bumps. Bump maping can be other things though like Enviromental Maping which is were you have a texture which the red and green channels hold texture cooridnate offsets which is usually used to sample a texture holding a reflection of the enviroment. So as you can imagine its usually used for bumpy reflections.   