Units

In order to basically use SVG, all you need to understand is how outer dimensions work. But to create more complex designs, you need to understand how inner dimensions work.

You can use different units in SVG, such as, for example: px, em, ex, pt, pc, cm, mm, in, and percent.

There are also coordinate system units, or user space units, which by default correspond to pixels, so you can omit the units for dimensions and coordinates if you are using pixels.