Kohanim and Leviim כהנים ולוויים
The descendants of Aharon and the tribe of Levi — servants of the sanctuary, who received no portion in the Land.
The tribe of Levi was the only one not involved in the golden calf and the only one to receive no territory: «the Lord is his portion». The Levites lived in forty-eight cities scattered among the other tribes and were supported by tithes. Their work in the Temple was song, guarding, carrying and teaching; the Rambam extends the image, saying anyone who sets himself apart for service takes on the spirit of Levi.
Within the tribe the kohanim, direct descendants of Aharon, held a particular place: they performed the service, blessed the people with the priestly blessing, ate of the offerings, and kept additional restrictions of purity and marriage.
After the destruction the service ceased but the status remained: a kohen is called first to the Torah, blesses the congregation, and redeems firstborn sons.