Table of Contents## Using Default User Coordinates

Entire Site

When you do not use unit specifiers on your `<svg>`

element, the viewer sets up a
coordinate system where the horizontal, or
*x*-coordinate, increases as you go to the right, and
the vertical, or *y*-coordinate, increases as you
move vertically downward. The upper left corner of the viewport is
defined to have an *x*- and
*y*-coordinate of zero.^{[1]} This point, written as (0, 0) is also called the origin.
The coordinate system is a pure geometric system; points have neither
width nor height, and the grid lines are considered infinitely thin.
We’ll return to this subject in Chapter
3.

Example 2-1 establishes a
viewport two hundred pixels wide and two hundred pixels high, then draws
a rectangle whose upper left corner is at coordinate (10, 10) with a
width of 50 pixels and a height of 30 pixels.^{[2]} Figure 2-1 shows
the result, with rulers and a grid to show the coordinate system.