A ball gown is worn for ballroom dancing and only the most formal social occasions according to rules of etiquette. It is traditionally a full-skirted gown reaching at least to the ankles, made of luxurious fabric, delicately and exotically trimmed. Most versions are cut off the shoulder with decollete necklines. Such gowns are typically worn with a stole (a formal shawl in expensive fabric), cape or cloak in lieu of a coat, "good" (couture or vintage) jewellery and opera-length gloves. Standard accessories are dancing shoes and a clutch style evening bag. Where "state decorations" are to be worn, they are on a bow pinned to the chest, and married women wear a tiara if they have one. The ball-gown shape has changed little since the mid-19th century. Although artificial fabrics are now sometimes used, the most common fabrics are satin, silk, taffeta and velvet with trimmings of lace, pearls, sequins, embroidery, ruffles and ruching.

According to rules of etiquette and attire, ladies must wear a ball gown to events where men are required to wear white tie attire. The elements of ladies' white tie attire could include:

A ball is a round, usually spherical but sometimes ovoid, object with various uses. It is used in ball games, where the play of the game follows the state of the ball as it is hit, kicked or thrown by players. Balls can also be used for simpler activities, such as catch, marbles and juggling. Balls made from hard-wearing materials are used in engineering applications to provide very low friction bearings, known as ball bearings. Black powder weapons use stone and metal balls as projectiles.

Although many types of balls are today made from rubber, this form was unknown outside the Americas until after the voyages of Columbus. The Spanish were the first Europeans to see bouncing rubber balls (albeit solid and not inflated) which were employed most notably in the Mesoamerican ballgame. Balls used in various sports in other parts of the world prior to Columbus were made from other materials such as animal bladders or skins, stuffed with various materials.

As balls are one of the most familiar spherical objects to humans, the word "ball" is used to refer to, or to describe, anything spherical or near-spherical.