During rapid prototyping, you really don't want to stop to make a commonly used icons. You also don't really want to put in placeholder icons because it often distracts reviewers from the core concept of the design.
People are lazy readers. They extrapolate most of the details from one visual cue that they can hang onto. When they are forced to read, their interpretation is clouded by the interpretation of the imagery.
Using appropriate icons improves visual comprehension and avoids distraction. So, here comes font awesome. I guess you can call this next-gen Winding. :) It has about 460 icons (I tried to manually count so I may be off by a dozen.).
It is a font. That means you can use it in any graphics tool, for example, Adobe Photoshop, Illustrator, Edge Animate, Axure, and Sketch.
For example, you want to use it on Adobe Illustrator: