The ampersand itself is thousands of years old but the name we use for it is only a couple hundred years old. It's a pictograph, or more accurately a logogram, and it’s so useful that Europeans have been addicted to it ever since it was invented.
It was invented by Marcus Tullius Tiro, who was born a slave but proved smart enough that Cicero freed him and hired him to keep track of speeches and things.
In Latin the way they said “and” was et. If you squish the two letters of et into a single character, what do you come up with? The ampersand: &.
Two, three and four hundred years ago this little squiggle was useful enough that children were taught it right along with their ABCs. At the end of the alphabet, it was usual during this period to have the ampersand as the last “letter” following the Z. So when kids were reciting their ABCs and they got to the end they didn’t stop at “w, x, y and z” instead they said “w, x, y, z and per-se and.” This is because for this symbol they were not only naming it, as they did all the other letters, they were assigning it a meaning, which the other letters didn’t have.
After years of saying “and per se and” the entire phrase was compressed down to a single word: ampersand.
courtesy podictionary, the podcast for word lovers