The Ionic order is narrower and taller in proportion than the Doric or Tuscan, though less so than the Corinthian. Always look for the capital, which has downward- and inward-curling spirals called volutes.
Sometimes these also project diagonally outwards, so that all four sides can look the same (called angle volutes). Otherwise they run back from the main outer edge, like a roll of bedding curled up at each end.
The shafts can be fluted or plain. On the cornice, there is usually a row of little blocks called dentils set just below the main overhang. The frieze can be plain or ornamented; sometimes it bulges outwards (called a pulvinated frieze).
Another variant has a band of decoration (called a swag or a festoon) stretching between the volutes.