A receiving line provides the Bride & Groom with an opportunity to talk with all of the guests.
When?
After the ceremony or at the beginning of the reception is the most common time.
Where?
Traditionally, the bride's parents start off the receiving line, then the new husband and wife, followed by the groom's parents. You can decide whether you would also like to include the honor attendants.
A Modern Twist?
Many couples are skipping the receiving line altogether and just mingling outside of the church or at the reception to greet guests more informally. There are no longer rules about the receiving line. It is up to the bride and groom to decide whether they want to stick with tradition.