Watercolor paper is a special type of paper that's used for painting with watercolors. It's different from regular paper because it's thicker and made to absorb water without getting too wet or falling apart.
There are different types of watercolor paper, and they come in different textures. The two most common textures are "cold-pressed" and "hot-pressed".
Cold-pressed paper is a little bumpy and has a texture that's sort of like the skin of an orange. It's not too bumpy, but it's not completely smooth either. It's a good choice if you want to create paintings that have a little bit of texture to them.
Hot-pressed paper, on the other hand, is very smooth. It's like a piece of regular paper that's been pressed and smoothed out. This type of paper is good if you want to create paintings that are very detailed and have a smooth finish.
There's also a type of watercolor paper called "rough" paper. Rough paper is very bumpy and has a lot of texture to it. It's good if you want to create paintings that have a lot of texture and depth.
So when you're choosing watercolor paper, you can think about the texture you want for your painting. If you want a smooth painting with lots of details, hot-pressed paper might be best. But if you want a painting with some texture and depth, cold-pressed or rough paper might be better.