Friction is the force distribution at the surface of contact between two bodies that prevents or impedes sliding motion of one body relative to the other. This force distribution is tangent to the contact surface and has, for the body under consideration, a direction at every point in the contact surface that is in opposition to the possible or existing slipping motion of the body at that point.

See this animation. A force is applied to body sliding on the floor. After sometime, the force is removed, but the body keeps moving, since it has already attained the velocity. However, after some time the body