Marriage vows are promises each partner in a couple makes to the other during a wedding ceremony. Marriage customs have developed over history and keep changing as human society develops. In secular ceremonies, vows can be chosen freely or created by the couple. Couples marrying within a religious tradition are often constrained to use the standard vows of that tradition's ceremony.
Many couples today opt to write their own vows. Inspirations are often taken from poems, movies, or music. Vows usually consist of what characteristics each bring out in each other, what they look forward to in life; how their lives changed once they met. Vows tend to last 2 - 3 minutes in length and are a public expression of love.
The original wedding vows for the Church of England, printed in The Book of Common Prayer, are:
Groom: I,____, take thee,_____, to be my lawful wedded Wife, 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 ordinance; and thereto I plight thee my troth.
Bride: I,_____, take thee,_____, to my lawful wedded Husband, to have and to hold from this day forward, for better for worse, for richer for poorer, in sickness and in health, to love, cherish, and to obey, till death us do part, according to God's holy ordinance; and thereto I give thee my troth.
Then, as the groom places the ring on the bride's finger, he says the following:
With this Ring I thee wed, with my body I thee worship, and with all my worldly goods I thee endow: In the name of the Father, and of the Son, and of the Holy Ghost. Amen.
This is only one from of vows and each religion has their own version of wedding vows.