It refers to the tendency of an object to remain at rest or to move at uniform speed along a straight line

The statement you provided refers to the concept of inertia. Inertia is a fundamental principle in physics, first introduced by Sir Isaac Newton in his first law of motion.

Here are the steps to understand this concept:

1. Newton's first law of motion, also known as the Law of Inertia, states that an object at rest tends to stay at rest, and an object in motion tends to stay in motion, unless acted upon by an external force.

2. This means that if an object is not moving, it will continue to stay still until something causes it to move. This could be anything from a person pushing it, to the ground shaking from an earthquake.

3. Similarly, if an object is already moving, it will continue to move at the same speed and in the same direction until something causes it to do otherwise. This could be anything from friction with the ground, to a person catching it.

4. The amount of inertia an object has is directly related to its mass. The more mass an object has, the more inertia it has. This means it's harder to start or stop the motion of objects with more mass.

5. Inertia is not a force, but rather a property of matter that describes how resistant it is to changes in motion.

6. Inertia is why we feel a jolt when a car starts moving or stops suddenly. Our bodies want to keep doing what they were doing (either staying still or moving), and it takes a force (the car seat pushing on us or the seatbelt holding us back) to change that.