What is a normal in OpenGL?

Question

I heard that I should use normals instead of colors, because colors are deprecated. (Is that true?) Normals have something to do with the reflection of light, but I can\'t find

Answer 1

Many things are now deprecated, including normals and colors. That just means that you have to implement them yourself. With normals you can shade your objects. It's up to you to make the calculations but there are a lot of tutorials on e.g. Gouraud/Phong shading.

Edit: There are two types of normals: face normals and vertex normals. Face normals point away from the triangle, vertex normals point away from the vertex. With vertex normals you can achieve better quality, but there are many uses also for face normals, e.g. they can be used in collision detection and shadow volumes.