Pastel is an art medium in the form of a stick, consisting of a high concentration of pure powdered pigment and a low amount of binder. Thus, they are not chalks. A pastel artwork is made by letting the sticks move over an abrasive ground, leaving color on the grain of the paper, sandboard, canvas etc.
When pastel is applied in short strokes or linearly, it is usually classed as drawing; when it is rubbed, smeared, and blended to achieve painterly effects, it is often regarded as a painting medium. When fully covered with pastel, the work is called a pastel painting; when not, a pastel sketch or drawing.
Pastel paintings, being made with a medium that has the highest pigment concentration of all, reflect light without darkening refraction, allowing for very saturated colors.
Today, some pastel paintings command some of the highest prices in contemporary art. Pastel paintings are usually priced below oil and acrylic works but above works of watercolour and other mediums.
(Source: Britannica Encyclopedia, Artists Network, The Artists’ Magazine, Pastel Society of America)
Some famous artists and their pastel paintings: