Drawing Techniques :: Lineweights and Linetypes
Lineweight, the basic syntax of technical drafting. Lines communicate the relationships between points, or the trajectories and magnitude of vectors. We can add more layers of meaning by controlling how lines are drawn to reflect visual intensity and coded meaning. Lineweight is the starting point for transforming a drawing from a bunch of lines to a collection of visual elements that describe form and meaning.
You must practice this, master value and difference. This is the language of architectural representation through drawing.