The symbol "&" is called an "ampersand". The symbol itself evolved from the word "Et", which is Latin for "and". If you write a capital E curvy like a backwards 3 and connect the t to it, it's easy to see how the symbol came about.
I just read somewhere that "ampersand" is an abbreviation of "and per se and". Well, that made no sense to me so I had to find the story. Thank you wikipedia.
In "the old days" (not sure how old that it) in school, & was included at the end of the alphabet as a kind of 27th letter. & was simply pronounce "and", as it should be.
Also, when refering to a letter of the alphabet which is also a word, like "a", "I", "o" and "&" ("o" was a word in the old days), you would put "per se" before the letter to mean the letter "by itself". So when reciting the alphabet you would say:
per se A, B, C, D, E, F, G, H, per se I, J, K, ... etc.
When you get to the end of the alphabet, then you say:
X, Y, Z and per se &. Which is "and per se and", which if you say it enough times slurs together to make "ampersand". (Just like those letters in the middle of the alphabet slur together to make the word "ellemenopee"... you know what I'm talking about it.)
So, I thought that was a pretty cool story. fwiw.