Jewish groups can be differentiated from each other and from non-Jewish groups by linguistic criteria. In some places, Jews spoke a domestic language different from that of their neighbors. Everywhere in the Middle East and Europe, Hebrew was used by Jews in prayer and for internal legal matters and sometimes for literature, usually religious, but sometimes secular as well. Aramaic, the language of the Talmud, was used for sacred purposes. Hebrew was an important source of words for jargons and argots, even among the uneducated. Until modern times, Jews wrote using Hebrew characters, whether they were writing in Yiddish, Judeo-Spanish, Arabic, Aramaic, or Persian.
In Arab and Persian lands ( including parts of Afghanistan and Central Asia), Jews generally spoke dialects intelligible to the coresident populations, but in the Balkans and Anatolia, as well as in Kurdistan and Azerbaijan, Jews spoke a distinct domestic language.
Classification of Jewish populations by domestic language (the language used for day-to-day affairs) provides a convenient taxonomy of groups.
Yiddish, the Germanic language used by East European Jews, was spoken by Eastern European Jews in Palestine. Although now replaced largely by Hebrew, some ultraconsevative Jews in Israel continue to use it.
Ladino (also called "Judezmo" and "Hakatia") is the Judeo-Spanish language spoken by Jews in the Balkans, Anatolia, and northern Morocco and by their descendants in Palestine/Israel and Egypt. In the Balkans, there are also communities of Romaniot Jews who still use a Jewish dialect of Greek.
In North Africa, the countries of the Fertile Crescent, and Yemen, Jews spoke various dialects of Arabic. The extent to which these dialects should be classified as Judeo-Arabic varies from place to place.
Aramaic (also called "Syriac") was the dominant language in the Fertile Crescent (except for Egypt) from the sixth century B . C . until the seventh to eight centuries A . D ., when it was superseded by Arabic. Forms of Aramaic are still used in a few small Christian groups such as the Nestorians and Jacobites, as well as by their Jewish neighbors in Kurdistan and Azerbaijan. Jews call this language either Targum or Jebali. Muslims in these areas speak either Turkic or Indo-European languages.
Persian (variously called "Farsi," "Dadi," "Tat," or "Tajik") is spoken by the Jews of Iran, Afghanistan, Tajikistan, Uzbekistan, and Daghestan. In Soviet Central Asia, Jews tended to adopt the Russian culture earlier than their Muslim neighbors.
Georgian (Gruzini), the language of Soviet Georgia, is spoken by Jews in and from that region.
Finally, it is likely that some small Jewish communities adopted languages other than these from their neighbors.