A uses to address B, then B also uses to address A. While people may transition quickly from to , such transition presumes mutual agreement. Use of without consent of the other person is likely to be viewed as poor conduct or even as an insult (or, in the case of opposite-sexed people, overly flirtatious), particularly if the other party maintains using . Historically, the rules used to be more class-specific: as late as at the end of the 19th century, it was accepted in some circles (in aristocracy and especially gentry) that was to be used also between friends, between husband and wife, and when addressing one's parents (but not one's children), all of which situations today would strongly call for using . Meanwhile, up to this day, common people, especially those living in rural areas, hardly ever use the polite . Russian and Belarusian speakers online uphold the distinction and mainly use for strangers, although in the earlier days of internet it was more common and expected to use to address everyone. The choice between and is closely related to, yet sometimes different from, the choice of the addressing format—that is, the selection from the first name, patronymics, last name, and the title to be used when addressing the person. Normally, is associated with the informal addressing by first name only (or, even more informally, by the patronymic only), whereas is associated with the more formal addressing format of using the first name together with patronymics (roughly analogous to "title followed by last name" in English) or the last name together with a title (the last name is almost never used together with either of the other two names to address someone, although such combinations are routinely used to introduce or mention someone). However, nowadays, can also be employed while addressing by first name only. In Ukrainian, the present practice is essentially the same as in Russian, historically this was primarily in the Eastern, Russian-ruled part of Ukraine. Until about 1945, due to Polish influence, the practices in the former Galicia and Volyn regions, tended to more closely resemble the Polish practices, as described below. But since those areas became annexed to the Soviet Union, the East Ukrainian and Russian practices have become prevalent all over Ukraine, with the , , , etc. forms only being preserved in the émigré diaspora. Serbo-Croatian In all standard forms of Serbo-Croatian,