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", "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.

The origins of European engagement in marriage practice are found in the Jewish law (Torah), first exemplified by Abraham, and outlined in the last Talmudic tractate of the Nashim (Women) order, where marriage consists of two separate acts, called erusin (or kiddushin, meaning sanctification), which is the betrothal ceremony, and nissu'in or chupah, the actual ceremony for the marriage. Erusin changes the couple's interpersonal status, while nissu'in brings about the legal consequences of the change of status. (However, in the Talmud and other sources of Jewish law there is also a process, called shiduchin, corresponding to what today is called engagement. Marrying without such an agreement is considered immoral. To complicate matters, erusin in modern Hebrew means engagement, not betrothal.)

This was later adopted in ancient Greece as the gamos and engeysis rituals, although unlike in Judaism, the contract made in front of witness was only verbal. The giving of a ring was eventually borrowed from Judaism by Roman marriage law, with the fiancé presenting it after swearing the oath of marriage intent, and presenting of the gifts at the engagement party.

Betrothal (also called "espousal") is a formal state of engagement to be married.^{[additional citation(s) needed]}

Typical steps of a match were the following:

The exact duration of a betrothal varies according to culture and the participants’ needs and wishes. For adults, it may be anywhere from several hours (when the betrothal is incorporated into the wedding day itself) to a period of several years. A year and a day are common in neo-pagan groups today. In the case of child marriage, betrothal might last from infancy until the age of marriage.