Coordinates

The coordinate system expects positive values on every axis. The world map is generated from the origin point of x: 0, y: 0, z: 0, extending to x: world width in blocks, y: world height in blocks, z: world depth in blocks.
Some misconception can arise from the coordinate system, as the in-game HUD displays coordinates based on the center point of the x and z axis of the world, and the player's relation to them.
Example: For a world size of 1000000 blocks in width and depth, the absolute player position on spawn would be x: 500000, z: 500000. In the HUD, this would be displayed as x: 0, z: 0

Notation

For use in commands, coordinates use the following notation.

Coordinate	Explanation
x	Relative to the center of the world.
=x	Absolute. Relative to the world as a whole.
~x	Relative to the player.

Example: Teleport to the absolute coordinates 0, 50, 0 (Note that the Y value is by default interpreted as an absolute value)
/tp =0 50 =0