+, , and =
A constant fascination is the source and evolution of mathematical symbols. For example, the addition/subtraction symbols + and  first appeared in Europe in the 15th century.
The great mathematician Leibniz tried to impose the adoption of a symbol for multiplication, advocating at least six different options: the dot, the cross, a cup, a comma, a semicolon, and an asterisk. So, why did some symbols win out and are in use today?
Or, consider these multiple options for the equal sign:
The "winner" was Robert Recorde's symbol, first used in his The Whetstone of Witte (1557). In this book, Recorde wrote: "To avoid the tedious repetition of these words: "is equal to", I will set (as I do often in work use) a pair of parallels, or Gemowe lines, of one length (thus =), because no two things can be more equal."
This is a small glimpse of the fascinating history of mathematics. Yet, I wish more people found it as fascinating!
Source: Adapted from J. Fujii's Intro. to Elements of Mathematics, 1961, pp. 1920
