Especially in Western cultures, an engagement ring is a ring indicating the that the person wearing it is engaged to be married. In the United Kingdom and the United States, engagement rings are traditionally worn only by women, and rings can feature gemstones. In other cultures men and women usually wear matching rings, which can be plain. In some cultures, engagement rings are also used as weddings rings.

Conventionally, the woman's ring is presented as a betrothal gift by a man to his prospective spouse while he proposes marriage or directly after she accepts his marriage proposal. It represents a formal agreement to future marriage. Rings can be bought by the man, the couple together, or by each partner for the other.

In the United States and the United Kingdom, it is worn on the left hand ring finger, while in Poland and Ukraine, it is customary for the ring to be worn on the right hand. In Germany, the ring is worn on the left hand while engaged, but moved to the right hand when married. Similar traditions purportedly date to classical times, dating back from an early usage reportedly referring to the fourth finger of the left hand as containing the vena amoris or "vein of love".

Before agreeing to marry, a couple may choose to buy and wear pre-engagement rings, also called promise rings. After marrying, the couple may wear both engagement rings and wedding rings, or just their wedding rings, as they prefer.