A worldline (or world line) is the path of an object through time and space. Ignoring relativistic effects, this corresponds to a function mapping time to position. Given relativity, such a mapping depends upon the frame of reference. A worldline is defined within a 4-dimensional spacetime in which the path through time and space is unique, such that the equivalent line in any frame of reference can be produced through a transformation implied by the relativity theory (there is a transformation associated with special relativity and a more complex one for general relativity). Spacetime diagrams attempt to show some of the characteristics of worldlines.