The friction coefficient is a numerical value that represents the amount of friction between two surfaces in contact. It is calculated by dividing the force of friction by the normal force pressing the two surfaces together. This value helps to understand how easily one object can slide over another, which is important in various applications, such as engineering and physics. There are two main types of friction coefficients: static and kinetic. The static friction coefficient applies when objects are not moving relative to each other, while the kinetic friction coefficient applies when they are sliding. Different materials, like rubber and metal, have different friction coefficients, affecting their grip and movement.