Etaoin shrdlu (/ˈɛtiˌɔɪnˈʃɜrdluː/)[1] is a nonsense phrase that sometimes appeared in print in the days of “hot type” publishing because of a custom of type-casting machine operators. It appeared often enough to become part of newspaper lore.
It is the approximate order of frequency of the 12 most commonly used letters in the English language.[2]