The Lesson

The x-coordinate is the first number in the pair of numbers used to describe Cartesian coordinates. For example, in the Cartesian coordinates (2, 4), the x-coordinate is 2 (the number on the left):

What Does the X-Coordinate Mean?

The x-coordinate tells you how far across the horizontal x-axis a point is on a graph (measured from the origin). If a point has Cartesian coordinates (2, 4), the point would be 2 units along the x-axis. The image below shows what we mean by a point being 2 units along the x-axis (measured from the origin):

Note: The x-axis is labelled with numbers (0, 1, 2, 3...) so you can measure how far across the point is.

The X-Coordinate Can Be Positive...

If you go right along the x-axis (starting at the origin, where it crosses the y-axis), it is labelled with positive numbers (0, 1, 2, 3...). The x-coordinate of any point to the right of the y-axis is positive. Imagine a point had an x-coordinate of 4. It would be 4 units to the right of the y-axis:

...Or the X-Coordinate Can Be Negative

If you go left along the x-axis (starting at the origin, where it crosses the y-axis), it is labelled with negative numbers (0, −1, −2, −3...). The x-coordinate of any point to the left of the y-axis is negative. Imagine a point had an x-coordinate of −4. It would be 4 units to the left of the y-axis:

Which Axis Is Which?

The x is a cross - so the x-axis goes across! The y-axis must go up.