There are three basic column styles for single-family homes, derived from ancient Greek architecture.
The Doric column is the oldest and simplest Greek style--its found on the Parthenon in Athens. This column features fluted sides, a smooth rounded top, or capital, and no separate base.
Ionic columns are identified by the scroll-shaped ornaments at the capital, which resemble a ram's horns. The Ionic column rests on a rounded base.
Corinthian columns are the latest of the three Greek styles and show the influence of Egyptian columns in their capitals, which are shaped like inverted bells. Capitals are also decorated with olive, laurel, or acanthus leaves. Corinthian columns rest on a base similar to that of the Ionic style.
In modern times, features of the three styles were mixed. Greek-influenced columns are frequently found in Greek Revival, Neoclassic, and Southern Colonial homes. Later Neoclassic versions (beginning in late 1800s and early 1900s) of these columns were often thinner and didn't have fluting.
Although Greek-influenced columns are by the far the most widely used in modern architecture, other column styles also occur.
Egyptian columns are thought to be modeled after the shape of the lotus flower indigenous to the Nile. These columns taper out at the top and are often ornamented with palm-like leaves near the capital. Other features include horizontal rings about one-quarter and three-quarters of the way up the shaft. Variations on these columns appeared in Egyptian Revival homes built during the mid-1800s.
Romanesque columns were used by American architect Henry Hobson Richardson in the mid-1800s to support the massive Roman arches in his Romanesque Revival homes. These squat, square columns often rest on massive, trapezoid-shaped bases, or piers, and often have floral or other decorations on their capitals. Simpler pier columns, often with wider bottoms than tops, are also common in Mission and Craftsman homes.