1. The nature of the surfaces in contact: This refers to the materials of the objects and their surface roughness. Smoother surfaces generally have lower friction than rougher surfaces. For example, ice has a much lower friction coefficient than sandpaper.
2. The force pressing the surfaces together: This is known as the normal force. The greater the force pushing the objects together, the greater the friction between them. For example, if you push a heavy box across the floor, it will experience more friction than a light box pushed with the same force.
