The document discusses the three main Greek architectural orders - Doric, Ionic, and Corinthian. Each order is defined by its capital and has distinguishing characteristics. The Doric order is the oldest and simplest, characterized by a plain capital. The Ionic order has a scroll-like capital and more ornate features. The most decorative is the Corinthian order, which has a capital adorned with acanthus leaves. The orders were used to construct many Greek temples and represented different ideals.