Masks are known as ta'l in Korean, but they are also known by many other names such as kamyon, kwangdae, ch'orani, t'albak and t'albagaji. Korean masks typically have black cloth attached to their sides in a manner designed to cover the back of the head of the wearer and to simulate black hair. A t'alch'um is really more than its literal meaning of "mask dance," but is also a drama in which persons, animals or supernatural  beings players are portrayed through the media of masks and dance.

Masks and mask dances developed in Korea in prehistoric times. Traditional masks fall into two categories: religious masks and artistic masks. Some religious masks were considered sacred, the focus of worship in shaman shrines and revered periodically with rites in which offerings were made. Other religious masks were used to ward off evil spirits. These include the Pangsangshi, which until recently, were often seen at the head of  funeral processions to ensure the departed would not fall victim to malignant forces of the spirit world.  Artistic masks were mostly used in dance and drama. However, these also had religious functions to some extent. Most Korean t'al are solid but some have moving parts like the eyeballs of the Pangsangshi mask, the mouth of the lion mask and the winking eyes of some masks used in dance-drama. Of special note are the masks featured in a mask dance-drama developed in the Hahoe region. They are two-piece constructions, the chin separate from the upper part but connected by strings to permit expression and the semblance of speech by  the mask-character. T'al are not only characterized by their respective roles but also by the fact they are modelled on the  bone structure of the typical Korean face. However, the faces s  portrayed are grotesque, their features greatly exaggerated, and are painted in bright, striking colors.

Masks are made of paper, wood, gourd and fur. Paper masks and gourd masks are prevalent, because they are simpler to make and also because they are lightweight and thus more convenient to wear while dancing. Red, black, white and other primary colors are ones most favored to effectively imbue masks with their specific and particular characters. The colors also identify the gender and age of the characters. The mask representing an old person is black, whereas that for a young man is red and that of a young woman, white. In traditional lore, black represents the north and winter while the red stands for the south and summer. In many of the t'alch'um dramas, the character of a young man always wins in contest against an older adversary, symbolizing the perennial triumph of summer over winter.   

In this sense, t'alch'um is a vestige of ancient fertility rites. Most masks depict human faces but some represent deities, and  others are of animals, real and imaginary. From a sociological point of view, an interesting feature of Korean mask culture is that those representing the yangban, the upper-class landed gentry, are almost always deformed in one way or another by harelips, sometimes cleaved in both upper and lower lips, lopsided mouths, distorted noses or squinted eyes - a telling reflection of the commoners' hostility toward this privileged class.
Mask dance-dramas are basically forms of folk art which developed naturally among the common people of the Chosun Dynasty (1392-1910). They vary slightly according to region and the performer but they all share fundamental characteristics. They derive essentially from a sense of rebellion felt by the common people toward the reality of their lives. While on the one hand some are quasi-religious in nature, embodying exorcism rites or ritual dances, others are biting satires in which human weaknesses, social evils and the privileged class are all parodied. Like the folk literature of the time, they appealed to their audiences by ridiculing apostate  Buddhist monks, decadent noblemen, and shamans.

The conflict between an ugly wife and a seductive concubine is another popular theme. A mask dance-drama will consist  of several sections, but they are quite different from the acts of a modern play. They are rather a loose presentation of several  different episodes in an omnibus style. Because the dialogue  has been passed down in an oral tradition, it is more considered basic material on which players can improvise rather than  something to which absolute faithfulness should be rendered.  Similarly, the dance component can be lengthened or shortened freely, so that the same performance can last between three or four hours to the whole night until daybreak.

With regional variations, the mask dance-drama was generally performed on the First Full Moon, Buddha's Birthday on the Eighth of the Fourth Moon, Tan-oh Festival and Ch'usok. It was also performed at festive occasions of the state or at rituals to supplicate for rain. Lively dance accompanied by vigorous music from three-string, six-wind and percussion instruments form the major part of a mask dance-drama performance, with the players stopping to deliver their lines with a great deal of gesticulation. Many of the roles do not have any dialogue of their own but act out their part in pantomime, their extraordinarily stylized masks conveying the dramatic impact of their  characters.  

The dance enlivens the drama and serves to round off each scene but is also performed without any regard to the progress of the plot. The most remarkable feature of Korean mask dance-drama in its traditional form is the enthusiastic participation of the audience. With the encouragement of the players, toward the end of a performance there is little distinction between them and the audience as they join together in robust dance and bring it to a truly affirmative life-enhancing finale.