Pilaster in the context of "Crown moulding"

An order in architecture is a certain assemblage of parts subject to uniform established proportions, regulated by the office that each part has to perform.Coming down to the present from Ancient Greek and Ancient Roman civilization, the architectural orders are the styles of classical architecture, each distinguished by its proportions and characteristic profiles and details, and most readily recognizable by the type of column employed. The three orders of architecture—the Doric, Ionic, and Corinthian—originated in Greece. To these the Romans added, in practice if not in name, the Tuscan, which they made simpler than Doric, and the Composite, which was more ornamental than the Corinthian. The architectural order of a classical building is akin to the mode or key of classical music; the grammar or rhetoric of a written composition. It is established by certain modules like the intervals of music, and it raises certain expectations in an audience attuned to its language.

Whereas the orders were essentially structural in Ancient Greek architecture, which made little use of the arch until its late period, in Roman architecture where the arch was often dominant, the orders became increasingly decorative elements except in porticos and similar uses. Columns shrank into half-columns emerging from walls or turned into pilasters. This treatment continued after the conscious and "correct" use of the orders, initially following exclusively Roman models, returned in the Italian Renaissance. Greek Revival architecture, inspired by increasing knowledge of Greek originals, returned to more authentic models, including ones from relatively early periods.

In classical architecture, the frieze /friːz/ is the wide central section of an entablature and may be plain in the Ionic or Corinthian orders, or decorated with bas-reliefs. Paterae are also usually used to decorate friezes. Even when neither columns nor pilasters are expressed, on an astylar wall it lies upon the architrave ("main beam") and is capped by the moldings of the cornice. A frieze can be found on many Greek and Roman buildings, the Parthenon Frieze being the most famous, and perhaps the most elaborate.

In interiors, the frieze of a room is the section of wall above the picture rail and under the crown moldings or cornice. By extension, a frieze is a long stretch of painted, sculpted or even calligraphic decoration in such a position, normally above eye-level. Frieze decorations may depict scenes in a sequence of discrete panels. The material of which the frieze is made may be plasterwork, carved wood or other decorative medium.

In architecture, the capital (from Latin caput 'head') or chapiter forms the topmost member of a column (or a pilaster). It mediates between the column and the load thrusting down upon it, broadening the area of the column's supporting surface. The capital, projecting on each side as it rises to support the abacus, joins the usually square abacus and the usually circular shaft of the column. The capital may be convex, as in the Doric order; concave, as in the inverted bell of the Corinthian order; or scrolling out, as in the Ionic order. These form the three principal types on which all capitals in the classical tradition are based.

The Composite order was formalized in the 16th century following Roman Imperial examples such as the Arch of Titus in Rome. It adds Ionic volutes to Corinthian acanthus leaves.

In European architectural sculpture, an atlas (also known as an atlant, or atlante or atlantid; plural atlantes) is a support sculpted in the form of a man, which may take the place of a column, a pier or a pilaster. Another Greek term for such a sculptural support is telamon (plural telamones or telamons).

The term atlantes is the Greek plural of the name Atlas—the Titan who was forced to hold the sky on his shoulders for eternity. The alternative term, telamones, also is derived from a later mythological hero, Telamon, one of the Argonauts, who was the father of Ajax.

Fluting in architecture and the decorative arts consists of shallow grooves running along a surface. The term typically refers to the curved grooves (flutes) running vertically on a column shaft or a pilaster, but is not restricted to those two applications. If the scoops taken out of the material meet in a sharp ridge, the ridge is called an arris. If the raised ridge between two flutes appears flat, the ridge is a fillet. Fluted columns are common in the tradition of classical architecture but were not invented by the ancient Greeks, but rather passed down or learned from the Mycenaeans or the Egyptians.

Especially in stone architecture, fluting distinguishes the column shafts and pilasters visually from plain masonry walls behind. Fluting promotes a play of light on a column which helps the column appear more perfectly round than a smooth column. As a strong vertical element it also has the visual effect of minimizing any horizontal joints. Greek architects viewed rhythm as an important design element. As such, fluting was often used on buildings and temples to increase the sense of rhythm. It may also be incorporated in columns to make them look thinner, lighter, and more elegant.

Astylar (from Gr. ἀ-, privative, and στῦλος, a column) is an architectural term given to design which uses neither columns nor pilasters for decorative purposes; thus the Riccardi and Strozzi palaces in Florence are astylar in their design, as opposed to Palladio's palaces at Vicenza, which are columnar.

Crown molding (interchangeably spelled crown moulding in British and Commonwealth English) is a form of cornice created out of decorative molding installed atop an interior wall. It is also used atop doors, windows, pilasters and cabinets.

Historically made of plaster or wood, modern crown molding installation may be of a single element, or a build-up of multiple components into a more elaborate whole.