Definition:Cartesian Coordinate System/X Coordinate

Definition
Consider a cartesian coordinate plane with an $x$-axis and a $y$-axis.

Let a point $Q$ be positioned on the plane.

The distance of the line segment from $Q$ to the $y$-axis is known as the $x$ coordinate and (usually) denoted $x$.

If $Q$ is to the right of the $y$-axis, then $x$ is positive.

If $Q$ is to the left of the $y$-axis, then $x$ is negative.

The $x$ coordinate of all points on the $y$-axis is zero.

Also known as
An archaic term for the $x$ coordinate which is sometimes seen is abscissa.

Also see

 * Definition:Y Coordinate