https://www.mycadsite.com/tutorials/level_4/different-types-of-dimensions-in-autocad-4-11a.html
This tutorial will explain the different types of dimensions which are commonly used in AutoCAD and help you understand their differences. A good AutoCAD drawing will convey the needed information clearly and accurately. Dimensioning is used to let the drawing reader know what size each length or curve is, without having to open the drawing and measure it. If your dimensions are inaccurate, you will not be working in CAD for very long, no matter how accurate your drawing is. Learn when each dimension is needed and how to use it.
