Here's a look at how the ceremony is going to go down...
Before the service, beginning at 10:35 a.m. local time, Luke Bond, the assistant director of music at St George's Chapel, inside Windsor Castle, will take to the organ to perform five pieces of traditional, religious and classic music.
The orchestra -- which is "made up of musicians drawn from the BBC National Orchestra of Wales, the English Chamber Orchestra and the Philharmonia, conducted by Mr Christopher Warren-Green," according to the program -- will then begin playing their set of seven classical musical compositions.
At 11:25 a.m., members of the royal family will arrive at the church, and are to be greeted by The Right Reverend David Conner, Dean of Windsor, who will also lead the beginning of the service. "Those in the Quire stand as they are conducted to their places," the Order of Service explains.
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Prince Harry and his best man, older brother Prince William, are scheduled to arrive at the west door of the church at 11:40, where they will be conducted by the Dean of Windsor to the Bray Chantry, where the ceremony will commence.
At precisely 11:42, Prince Charles and wife Camilla Parker Bowles will arrive, and be greeted by the Vice-Dean of Windsor, and are presented to their places.
Markle's mother, Doria Ragland, is then expected to arrive at 11:45, where she will be received by the Dean of Windsor and conducted to the Quire at the front of the chapel.
Her Majesty The Queen will arrive at 11:52, and will also be received by the Dean of Windsor, and conducted to the Quire, as everyone in attendance stands and a fanfare sounds. Then, all members of the choir and clergy will move in procession through the church.
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After reading a passage about the symbolism and importance of marriage as an institution, Right Rev. Conner will lead everyone in a hymn, before the Archbishop of Canterbury, the Most Reverend and Right Honourable Justin Welby, leads the solemnization.
Beginning with "The Declarations," the Archbishop of Canterbury will first ask for any possible objections.
"First, I am required to ask anyone present who knows a reason why these persons may not lawfully marry, to declare it now," the Archbishop will ask, according to the Order of Service. Assuming there are no wild, rom-com-esque last-minute declarations of love, the ceremony will proceed as planned.
Next are the exchanging of declarations, as read by the Archbishop. Both bride and groom will be asked if they will love, comfort, honor, and protect one another, "forsaking all others," and if they will "be faithful" to each other, "as long as you both shall live?"
The Order of Service then presumes that both parties will reply, "I will."
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The final part of the declarations are directed at their families. The archbishop will ask, "Will you, the families and friends of Harry and Meghan, support and uphold them in their marriage now and in the years to come?"
Following the vows, all guests sit as The Lady Jane Fellowes reads from the Song of Solomon, followed by a motet -- a short piece of unaccompanied, sacred choral music -- performed by the Choir of St George’s Chapel.
Then, in one of the most interesting moments described by the Order of Service, Karen Gibson and The Kingdom Choir will perform a rendition of the iconic 1961 American R&B-Blues classic "Stand By Me."
"When the night has come / And the land is dark / And the moon is the only light we see / No, I won’t be afraid / No, I won’t be afraid / Just as long as you stand, stand by me," the program features the beloved tune's famed lyrics, as originally performed by Ben E. King.
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The unique and beautiful selection will precede the exchanging of vows, where Markle and the prince will hold hands and promise to "have and to hold from, this day forward; for better, for worse, for richer, for poorer, in sickness and in health, to love and to cherish, till death us do part; according to God’s holy law."
Then, Prince Harry and his betrothed will both exchange rings. This is in contrast to Prince William's wedding to Kate Middleton in 2011, where the elder Prince presented a ring to the bride, but did not wear one himself.
Following the exchange, the Archbishop with solemnize the ceremony with a proclamation of their love. Joining their right hands together, the Archbishop will declare, "Those whom God has joined together let no one put asunder." He will then bless the marriage.
After the blessing, all guests will sit or kneel for the prayers, which will be led by Archbishop Anba Angaelos The Reverend Prebendary Rose Hudson Wilkin, followed by a hymn asking for guidance from Christ, and then another blessing from the Dean of Windsor.
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After the signing of the registers, accompanied by numerous orchestral numbers, it will be time for the procession of the bride and bridegroom, which is where attendees and viewers will be treated to another interestingly modern piece of music.
First, there will be the traditional "Symphony no. 1 in B-flat -- Allegro," a classical composition by William Boyce. However, the second song during the procession will be Etta James' rendition of "This Little Light of Mine," which is a beautiful thematic compliment to "Stand By Me."
As explained by Kensington Palace, "Copies of the Order of Service will be given to all those attending Windsor Castle." This 21-page document will definitely be the ultimate Royal Wedding collector's item.