1. The base. Most columns rest on a round or square base.
2. The shaft. The length of the column. It may be smooth, fluted or feature carved designs.
3. The capital. The top of the column may be simple or elaborately designed- it is usually with careful observation of the capital that a column can be classified as Doric, Ionic, or Corinthian.
Columns-Doric
Of the three column designs, Doric columns are the simplest. Their capitals are made of a circle topped by a square. The shaft is simple, featuring 20 straight sides or a smooth surface that end at a simplistic base that is not a capital.
Columns-Ionic
Ionic shafts are generally taller than those on Doric columns. They also featured flutes, which are grooved patterns carved into them from top to bottom. Columns of the Ionic style look more slender and appear perfectly straight due to entasis- the application of curvature that make the column look straight at a distance. Ionic capitals are designed to look like scrolls above the shaft.
Columns-Corinthian
The Corinthian order is the most decorative of the three styles. Corinthian also uses the method of entasis to make the shafts appear straight to the human eye. The Corinthian capitals have flowers and leaves below a small scroll that connect to the shaft and end on a circular or square platform that is the base. All columns of the Pantheon are of this style.