Speaking of Stephen Sondheim, on this day in 1819, Jacques Offenbach, who most consider the "inventor" of the operetta, was born in Cologne. The operetta (literally, "little opera"), differs from a full-blown opera because there is often acting, or moments where the libretto, or text, is spoken between songs. An opera libretto, of course, is sung straight through.
And while you probably haven't heard of any of Offenbach's operettas, certainly you'd recognize HMS Pinafore or The Pirates of Penzance, by... READ ON