Hi. "Avete" is used for the plural but also for the very formal situations: With unknown people and/or more old than you. Between guys is not used. Bye. (: EDIT: Yes, I forgot, also indicates the level of familiarity you have with a person, sorry. But, isn't less of an honorific form, IS an honorific form. I add that "avete" is not used much nowadays as honorific form, in general is used the "lei". Exemples: "AVETE avuto una buona giornata?" "HA avuto una buona giornata?" (Did you have a good day?) Bye. (:

Avete is basically used when addressing a group. "Voi avete" = "you(collective) have". When writing formally, you also use the "voi" conjugations when addressing the reader. Worth noting that changing "hai"->"ha"->"avete" is less of an honorific form, and more to do with your level of familiarity with that person.