What does "&" mean and where did it come from?

From Wikipedia:

An ampersand (&), also commonly called an "and sign," is a logogram representing the conjunction "and." The symbol is a ligature of the letters in et, Latin for "and." Its origin is apparent in the second example in the image to the right; the first example, now more common, is a later development.

The ampersand often appeared as a letter at the end of the Latin alphabet, as for example in Byrhtferð's list of letters from 1011.^[1] It is thought that teaching & as the last letter of the alphabet (... X Y Z and &), a common practice through the 19th century, led to its name, a corruption of the phrase "and per se and", meaning "and [the symbol which] by itself [is] and".^[2] The Scots and Scottish English name for & is epershand, derived from "et per se and" with the same meaning.

More info