Hi i was reading the chrome tutorial at elysiun at i saw something they said about environment maps. I saw a lot of other sites mention about it, but i didnt understand what they are .can someone explain them to me? 
Envmaps are a kind of texture, like image, clouds, blend etc.
They are normally used to fake reflaction, which can’t be calculated by blenders scanline renderer automatically (a ray-tracer could).
Metallic objects appear metallic because the reflect/mirror their surrondings. Envmap are used to fake metallic materials.
They also can be used to fake a mirror, reflections on water, etc.
Blender calculates envmaps by using the center point of an object like a camera and shoots an images in directions of the axis each. These shots are combined in the actual enviromentmap of relative size 3:2.
Order:
-X; -Y; X
-Z; Z; Y
An envmap texture is usually applied to the reflection coordinates of the object. They can be saved as images and loaded.
Ohh, so appyling the chrome effect is like reflecting the light, so we gotta use an env map on the object that has the chrome effect?
Yep. A raytracer would trace the light and the reflections. Blender can’t, so what you can do is take a snapshot from the chrome’s point of view and just paste it on the chrome. You use an empty as a second camera. (simplified)
I left a mini-tut in the thread ‘Env Mapping a Plane’. Hope it helps.