Sashtiaapdapoorthi (known also as "Sashti Aapda Poorthi" or "Sashti Poorthi") is a Hindu ceremony celebrating a marriage, akin to the renewal of marital vows and the "Silver Anniversary" in the West. Specifically, it marks simultaneously the 60th birthday of the husband and the wedding anniversary of the couple ("Sashti" - 60, "aApda" - years/life (as in Sagaptham), "poorthi" -"completion."
There are 60 years in a hindu calendar cycle. Each year has a name. When a person reaches 60, they enter the second cycle. This is reason enough to celebrate, having learned, entering married life, raising children, having devoted to the service of God and setting an example to the family and society.
Historically, because the husband would typically always be older than wife, Sashtiaapdapoorthi is celebrated when the husband (as opposed to the wife) turns 60. Widowed, divorced or remarried do not usually celebrate this ceremony.
The celebration is usually organized by the couple's children, younger siblings and grand children. In addition to various poojas poojas, part of the wedding ceremony is reenacted. The couple that is celebrating Sashtiaapdapoorthi are given blessings from elders who have themselves already celebrated Sashtiaapdapoorthi. After this, the now blessed couple in turn blesses all others participating or witnessing the ceremony who are younger than 60.