Assertion (A): Every point on the $x$-axis has its ordinate equal to 0. Reason (R): On the $x$-axis, the point is at zero vertical distance from the $x$-axis itself. Which is correct?

- **Origin**: (0, 0).
- **On $x$-axis**: $y=0$, so the form is (a, 0). Examples: (3, 0), (−5, 0).
- **On $y$-axis**: $x=0$, so the form is (0, b). Examples: (0, 7), (0, −2).
- **First-quadrant point**: both positive.
- **Third-quadrant point**: both negative.

Knowing which axis or quadrant a point belongs to is a quick check that you've plotted it correctly.