Use sparingly

The amper­sand is typo­graphic short­hand for the word and. The amper­sand is halfway between a ligature and a con­trac­tion, a styl­ized depic­tion of the Latin word et.

The amper­sand is one of the jaun­ti­est char­ac­ters. Font design­ers often use it as an oppor­tu­nity to show off. Tra­di­tional amper­sands take the shape of the word et. Mod­ern amper­sands are more styl­ized.

Amper­sands are com­pletely cor­rect when they’re part of a proper name (Fro­mage & Cra­cotte LLP) or an offi­cial cita­tion for­mat (Bus. & Prof. Code § 17200).

Past that, amper­sands should be han­dled like any other con­trac­tion: the more for­mal the doc­u­ment, the more spar­ingly they should be used. Here and there, but not every­where.