The Ionic order formed one of the three orders or organizational systems of Greek or classical architecture - as opposed to the other two orders: the Doric and the Corinthian.

The Ionic order originated in the mid-5th century B.C. in Ionia, the western coastlands of Asia Minor settled by Ionian Greeks.

Ionic columns stand on a base which separates the shaft of the column from the stylobate or platform. The capital of the ionic column has a characteristic scrolling volute on four corners.

The pictorial frieze provides the most characteristic feature of the Ionic order: it consists of a horizontal band of usually narrative pictorial carving that rests between the tops of the columns and the roof edge. In earlier Doric buildings this horizontal area had been left plain.

Renaissance and modern architectural theorists often interpret the Ionic Order as feminine in comparison to the Doric Order, and even liken the scrolling volutes to the circular hair-styles of women in Ionia.

Because no treatises on classical architecture survive earlier than that of Vitruvius, who worked in the time of Augustus, identification of meaning in architectural elements in the 5th and 4th centuries B.C. remains extremely tenuous.

Vitruvius certainly reports (in book 4 of his De Architectura) that the Doric has a basis of sturdy male body proportions while Ionic depends on "more graceful" female body proportions, but he does not name his sources.

The Parthenon, although it conforms mainly to the Doric order, also has some Ionic elements.