“And” is the only word that has its own unique symbol. Why, and where did it come from?
The Latin word for “and” is “et,” which when written in Old Roman cursive (uppercase E, lowercase t), looked like &. This is why “etc.,” short for “et cetera,” is sometimes written as “&c.”
The symbol we now know as the ampersand first appeared written on a mural in Pompeii in the 1st century A.D. As the centuries passed, it actually became accepted as the 27th letter of the English alphabet, although it has been dropped from the alphabet in the last two centuries or so.
The term “ampersand” comes from the phrase “et per se and,” which means something like “et, in other words, and” (not a literal translation).
Here is a short video that gives a nice summary of the ampersand’s history.