Shalom aleichem
Shalom aleikhem (Hebrew: שָׁלוֹם עֲלֵיכֶם shālôm ʻalêḵem; Yiddish: שלום־עליכם sholem aleykhem) is a greeting version in Hebrew, meaning "peace be upon you" (Pl.). The appropriate response is "aleikhem shalom", "upon you be peace".
This form of greeting is traditional among Jews throughout the world. It occurs six times in the Jerusalem Talmud. The greeting is more common amongst Ashkenazi Jews. Only the plural form עֲלֵיכֶם is used even when addressing one person. A religious explanation for this is that one greets both the body and the soul, but Hebrew does occasionally use the plural as a sign of respect (e.g. a name of God is Elohim אלוהים literally gods).
Other religions
Many religions share cognates to this greeting.
The related Muslim variation as-salāmuʿalaykum, is used by Muslims of innumerable lingual and ethnic backgrounds. (In Arabic السلام عليكم) As-salāmu alaykum and its variants are used by Muslims outside of the Arab world in Turkey, Indonesia, Central Asia, Iran, Sahel Africa, East Africa, and many other places. Aramaic and classical Syriac use Shlomo 'ahlaykhu which means peace for you.
Within the Catholic Church, "Peace be with you" is the initial liturgical greeting by a bishop at the celebration of Mass, while priests who are not bishops say "The Lord be with you." The response is "And with your spirit." A somewhat similar greeting used within the Mass by bishops and priests is "The peace of the Lord be with you always."