Pressure is the amount of force applied to a colored pencil by your hand as it moves across the paper. Artists deliberately vary their hand pressure to control color intensity, coverage, and the amount of pigment deposited onto the paper.
Light pressure generally allows more layers to be added while heavy pressure deposits more material and can burnish or flatten the paper's texture, limiting subsequent layering.
Learn more: How Pencil Pressure Affects Color, Blending, and Layering (coming soon)