An arcade is a succession of contiguous arches, with each arch supported by a colonnade of columns or piers. Exterior arcades are designed to provide a sheltered walkway for pedestrians; they include many loggias, but here arches are not an essential element. An arcade may feature arches on both sides of the walkway. Alternatively, a blind arcade superimposes arcading against a solid wall.

Blind arcades are a feature of Romanesque architecture that influenced Gothic architecture. In the Gothic architectural tradition, the arcade can be located in the interior, in the lowest part of the wall of the nave, supporting the triforium and the clerestory in a cathedral, or on the exterior, in which they are usually part of the walkways that surround the courtyard and cloisters.

A different, related meaning is "a covered passage with shops on one or both sides". Many medieval open arcades housed shops or stalls, either in the arcaded space itself, or set into the main wall behind. From this, "arcade" has become a general word for a group of shops in a single building, regardless of the architectural form.

The word "arcade" comes from French arcade from Provençal arcada or Italian arcata, based on Latin arcus, ‘bow’ (see arc and arch).

A related but ambiguous term is arcature, which is either a small arcade or a blind arcade.

Arcades go back to at least the Ancient Greek architecture of the Hellenistic period, and were much used by the Romans, for example at the base of the Colosseum. Church cloisters very often use arcading. Islamic architecture very often uses arcades in and outside mosques in particular. In Renaissance architecture elegant arcading was often used as a prominent feature of facades, for example in the Ospedale degli Innocenti (commissioned 1419) or the courtyard of the Palazzo Bardi, both by Filippo Brunelleschi in Florence.

The French architect, Bertrand Lemoine, described the period, 1786 to 1935, as l’Ère des passages couverts (the Arcade Era). He was referring to the grand shopping "arcades" that flourished across Europe during that period. A shopping arcade refers to a multiple-vendor space, operating under a covered roof. Typically, the roof was constructed of glass to allow for natural light and to reduce the need for candles or electric lighting. The 18th and 19th century arcades were designed to attract the genteel middle classes. In time, these arcades came to be the place to shop and to be seen. Arcades offered shoppers the promise of an enclosed space away from the chaos that characterised the noisy, dirty streets; a warm, dry space away from the harsh elements, and a safe haven where people could socialise and spend their leisure time. As thousands of glass covered arcades spread across Europe, they became grander and more ornately decorated. By the mid-nineteenth century, they had become prominent centres of fashion and social life. Promenading in these arcades became a popular nineteenth-century pastime for the emerging middle classes.

The inspiration for the grand shopping arcades may have derived from the fashionable open loggias of Florence however medieval vernacular examples known as 'butterwalks' were traditional jettied colonnades in British and North European marketplaces; examples remain for example in Totnes and Dartmouth in Devon. During the 16th-century, a pattern of market trading using mobile stalls under covered arcades was established in Florence, from where it spread throughout Italy. Examples of the earliest open loggias include: Mercato Nuovo (1547) by Giovanni Battista del Tasso (and funded by the Medici family); Mercato Vecchio, Florence by Giorgio Vasari (1567) and Loggia del Grano (1619) by Giulio Parigi.