RC is a logic relationship defined between fields in the same table or across tables. RCs can be used to create dependent structures and links between tables. RCs are defined in three steps: 1) Name the RC and select the source table. 2) Define the logic conditions for the RC. 3) Specify the field details for each logic condition, including comparing a present field to a source field or comparing a source field to a set value. RCs allow defining relationships that enforce referential integrity between related data.