Some facts about Helvetica:
1) Helvetica’s characters always have vertical or horizontal terminations on their strokes, never diagonal.
2) Helvetica is as much about the negative space surrounding the letters than about the lines that make up the characters themselves.
3) The negative space contained within the lowercase “a” closely resembles a teardrop.
4) It has monotone stroke weights.
5) It remains legible when in motion, one reason it’s popular for signage and automaker and airline logos.