The answers given by authorities in Jewish law to questions put to them; Heb. sheelot u-teshuvot, ‘questions and answers’. There are occasional references in the Talmud to letters sent by one Rabbi to another asking for information in matters of law but the Responsa activity proper dates from the period of the Geonim, when the practice developed of scholars addressing questions to the heads of the great Babylonian communities at Sura and Pumbedita in Babylonia, the foremost authorities in this period. Collections were made of the Geonic Responsa, especially those of Sherira Gaon and his son Hai Gaon, but while these collections were known to the medieval authorities they did not appear in print until as late as the nineteenth century. Essentially, the questions in the Responsa concern problems which arose out of new conditions, for which no direct answers could be found in the Talmud, the final authority for Jewish law. The leading Respondents through the ages, faced with new questions, tried to discover analogies in the Talmud and the later Codes and from time to time the replies in the Responsa served as sources for new Codes.