Jewish genealogy
Jewish genealogy is the study of Jewish families and the tracing of their lineages and history. The Pentateuchal equivalent for "genealogies" is "toledot" (generations). In later Hebrew, as in Aramaic, the term and its derivatives "yiḥus" and "yuḥasin" recur with the implication of legitimacy or nobility of birth. In Modern Hebrew, genealogy is generally referred to as "שורשים"/"shorashim", the Hebrew word for roots, or borrowing from the English, "גנאלוגי"/"genealogi". Since Judaism is not only a religious community but an ethnic group that claims descent from common ancestry, there has been significant interest in tracing Jewish descent. To this  day there are Jews who trace their descent from the ancient tribe of priests (kohanim) and levites (leviim) of the Jewish Bible and who still receive special recognition in areas such as the Jewish synagogue service. Due to the importance of Torah learning in the Jewish tradition, genealogical records of rabbis and Hasidic rebbes are carefully recorded and readily available. The Holocaust was a significant factor in stimulating the research of Jewish genealogy. Many Jews were tormented by questions of what and who had been lost. In response, a number of genealogical agencies were created, including the International Tracing Service  (ITS) in Arolsen, the Search Bureau for Missing Relatives in Jerusalem, and museum and resource Yad Vashem. CRARG (Czestochowa-Radomsko Area Research Group)(www.crarg.org) finds and translates Holocaust survivor lists and death lists from around Poland. Its database is one of the largest on the web, with over 300,000 records so far, covering hundreds of towns and consisting of more than 150 separate projects. Family pedigrees. Some Jewish families have preserved traditions relating to their tribal affiliation, based on partial genealogical records passed down generation after generation. In Yemen, for example, some Jews trace their lineage to Judah, others to Benjamin , while yet others to Levi and Reuben. Some Ashkenazi Jews have "Levi" and/or "Cohen" as surnames, probably because their ancestors were levites/cohanim. Of particular interest is one distinguished Jewish family of Yemen who traced their lineage to Bonai, one of the sons of Peretz, the son of Judah.