But almost as important as the wedding itself is what the bride wore. Here we look back at some famous weddings -- and the gowns.
In September 2006, all eyes were on John-John's bride, as she exchanged vows wearing a dress that became an iconic bridal style.
When Chan married her college sweetheart — Facebook's billionaire CEO — in May, she donned a relatively budget-friendly dress.
In August 2010, the former first daughter walked down the aisle in a strapless silk organza gown designed by a bridal fashion icon.
This upper-crust fashion editor got married to her wealthy Colombian fiance in 2007 wearing a voluminous gown fit for a princess.
The model-turned-actress said I do to her tennis-pro beau in 2009 wearing a form-fitting column dress.
Portia de Rossi
De Rossi made it official with her missus in August 2008 while wearing a halter dress with a billowing tutu skirt.
For her first marriage in 1966, to the Chairman of the Board, the 21-year-old actress sported her signature pixie cut and a minimalist look.
Hayek and her French billionaire groom held a lavish, star-studded ceremony in April 2009
For her first wedding, in 1954 — he was her Hollywood co-star — the fashion idol wore a garland of flowers in her hair and looked every bit the gamine.
The Hollywood starlet married European royalty in 1956 wearing a trendsetting gown that's copied by brides to this day.
When Jacqueline Bouvier exchanged vows with the future 35th U.S. president in 1953, she walked down the aisle and into the history books in a bouffant ball gown.
Kate captivated the world in 2011 when she married Prince William in a high-profile televised ceremony.
In 1993 she became the princess of this Middle Eastern country in a resplendent gold-trimmed gown.
The first lady and the president were married in October 1992 , and her dress reflected early-'90s style.
True to form, when she married a rock legend in 1969, the avant-garde artist's ensemble was as outré as her sound.
In 1981, Lady Diana Spencer arrived in true princess style to marry Prince Charles in London
The pop star-turned-entrepreneur bucked bridal fashion tradition when she married her Brit rocker beau in 2002.
This bombshell actress epitomized the swinging '60s when she married her second husband, a Hollywood producer.