As you would expect over thousands of years of use, study and refinement, every smallest subcomponent of the column has its name and variation, from the abacus to the cincture (see Figure below). These variations are the key to recognizing the classical order of the column, discussed below, but they are also what makes the design of contemporary columns so customizable, as the size, number and style of many of these components can be “mixed and matched” in almost limitless ways.

From top to bottom, the basic major components of columns past and present are:

The capital: the topmost section of the column. The many different profiles of a column’s capital, ranging from very simple to highly ornate, are key identifiers of its order. Depending on the style, the capital may have several “layers” of molding, including the flat abacus slab, the convex disc echinus, and a small convex molding, closest to the shaft, called the astragal, in modern columns usually referred to as the “bead.” A wide range of capitals is available in modern columns, either as part of standard styles, or separately as decorative capitals or custom designs. A standard cast column capital can be “cut at the bead” and replaced with a decorative capital.

The shaft: the vertical element of the column, most often cylindrical but sometimes square or octagonal. Shafts can be smooth or shaped with the vertical hollow grooves called “flutes.” The number and profile of flutes for each classical architectural order is carefully defined, but can be customized in modern columns. Square shafts are available with recessed panels in various sizes, shapes and panel molding. In many ancient columns, the shaft was composed of separate drums, fitted together with engineering skill that would be difficult to achieve today, and relatively resilient to seismic forces. Modern shafts are most often hollow, and can enclose structural supports, or equipment such as wiring and drainage spouts.

Square shafts—either tapered or untapered—are available now in many styles, particularly more contemporary ones. Round barrel cast columns without tapering are also often used for contemporary settings. But the majority of columns manufactured today are circular, with the subtle outward-inward curve known as entasis, often in the same dimensions described by Renaissance architects based on their measurements of ancient Greek and Roman buildings.

The base: In some of the oldest columns, including Egyptian and early Doric in Greece, the columns have no separate base but are placed directly on the floor or pavement. But most columns have a rectangular or square base molding, the lowest part of which is the plinth. The base molding can be quite varied, including for example the semi-circular torus and the ring called the cincture which can also sometimes be found at the top of the column. These are also elements that may be customized, or used with different styles of capital, in coordinated sets or new combinations.

Pilaster: Although not strictly speaking a part of the column, pilasters are ornamental elements that give the appearance of flattened columns and often appear directly behind columns, or sometimes on the sides of a doorway or window. Like columns, pilasters can be plain or fluted, and in the style of the classical orders.