Tooth of the paper
The grain (tooth) of your paper is very important when using coloured pencils, just as it is with watercolours. Rough tooth is when you can see the ridges on the paper more easily. It provides a grip for coloured pencils to bind to when layering. It also provides a distinctive texture to a piece. Smooth tooth is when the ridges are very fine and are harder to see. I find this type provides easier blending with coloured pencil work and watercolour work. It’s also easier for a medium to come off of the paper, though. There are levels of tooth in-between as well.