The first traveler who happened by after the wounded man was left on the side of the road was a priest, which at that time meant a leader of the Jewish religious hierarchy. Specifically, priests were descendants of Aaron, the brother of Moses and the first high priest of the Israelites. The priest passed by the wounded man by crossing to the other side of the road.
The second traveler to pass by was a Levite. Levites were also leaders of Jewish worship in the synagogue, but were not from Aaron's direct lineage. The Levite also crossed the road and did nothing for the injured traveler.
The third person was the Samaritan, a citizen of Samaria, a region that was much despised by residents of Galilee. The Samaritan gave first aid to the traveler, transported him to an inn, cared for him overnight, and left funds with the innkeeper to pay for further care.