D3: Domain & Range

What is Domain & Range in D3
&
What is the difference b/w them?

var scale = d3.scaleLinear()
.domain([d3.min(data), d3.max(data)])
.range([0, width - 100]);
basically is scale convertor, it says these outer data min and max have this 0 and max position in axis.
http://www.tutorialsteacher.com/d3js/axes-in-d3