* Motion is relative: There is no absolute "stillness" or "motionlessness" in the universe. Something is only considered in motion if it's changing its position *relative* to another object or point.
* Example: Imagine you're sitting in a train that's moving at a constant speed. You might feel stationary, but you're actually in motion relative to the ground outside. You're also in motion relative to someone standing on the platform, but you're stationary relative to the other passengers on the train.
* Frames of Reference: A frame of reference is simply a chosen point or set of points that we use as a standard to determine if something is moving or not. The most common frame of reference is the Earth, but we can use other frames like a moving car, the Sun, or even a distant galaxy.
In essence, motion is a comparison. You can't talk about motion without specifying what you're comparing the movement to.
