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An engagement or betrothal is the period of time between the declaration of acceptance of a marriage proposal and the marriage itself (which is typically but not always commenced with a wedding). During this period, a couple is said to be fiancés (from the French), 'betrothed', 'intended', 'affianced', 'engaged to be married', or simply 'engaged'. Future brides and grooms may be called fiancée (feminine) or fiancé (masculine), 'the betrothed', a 'wife-to-be' or 'husband-to-be', respectively. The duration of the courtship varies vastly, and is largely dependent on cultural norms or upon the agreement of the parties involved.

Long engagements were once common in formal arranged marriages, and it was not uncommon for parents betrothing children to arrange marriages many years before the engaged couple were old enough. This is still done in some countries.

Many traditional Christian denominations have optional rites for Christian betrothal (also known as 'blessing an engaged couple' or 'declaration of intention') that bless and ratify the intent of a couple to marry before God and the Church.