Uniform Rectilinear Motion (URM) refers to the movement of an object traveling in a straight line at a constant speed. In this type of motion, the object's velocity remains unchanged over time, meaning it covers equal distances in equal intervals, regardless of how small those intervals are. This concept is fundamental in physics and is often represented by the equation d = vt, where d is the distance traveled, v is the constant speed, and t is the time taken. URM is a simplified model that helps in understanding more complex motions in the study of mechanics.