When you tighten a nut on a bolt, how are you increasing

Solution 9DQ Step 1 of 3: Friction always exists in a bolted joint. On one side, it limits the efficiency to transform the torque into the desired preload, on the other hand it is necessary to keep the preload in the joint to prevent loosening of the parts.The torque value is dependent on the friction, present in the threads and between the torqued bolt head and nut, and the fastened material or washer if used.So by increasing torque we can increase the frictional force