Frame of reference
abstract coordinate system and the set of physical reference points that uniquely fix (locate and orient) the coordinate system and standardize measurement(s) / From Wikipedia, the free encyclopedia
In physics, a frame of reference, or reference frame, is a perspective that one uses to determine if an object is moving.[1] A frame of reference consists of an object or environment that is considered to be stationary. Typically the observer is at rest in the reference frame; in this context, the term is "observational frame of reference."
For example, when you see a ball roll down a street, you can tell the ball is moving because the frame of reference is the streets, whatever may be on the side of the roads, or the Earth. All of these are frames of reference.
All measurements of motion will be compared to a frame of reference.[2] Therefore, the most commonly used frame of reference is Earth itself, even though it moves. Stars are used as a frame of reference when discussing the motions of the Earth.
When we walk from one side of a ship to the other, our frame of reference is the ship; whether the ship is moving is not relevant to that frame of reference.