The Celtic Knot is one of the best known motifs in Celtic jewelry and art. The delicate twists and turns are found in ancient stone art and tattoos, in illuminated manuscripts- in fact, just about anywhere the Celtic people have travelled. Similar designs exist in Norse culture, and as far as China. 

The continual looping of the designs suggests themes of eternity and interconnectedness, and knots may have been made at one time to foil evil spirits. Interwoven figures of people and animals may have represented the interdependent nature of life-two or more knots laced together symbolize lovers, hunters and their prey, God and man, etc. Some knots were used as magical talismans for protection.

The more modern designs, such as those found in decorated Christian scriptures, were mainly decorative designs used for ornamentation. Other relatively modern designs include linked hearts and other "love knots," Christian crosses, harps, shamrocks, and other folk symbols, and so on.

The Celts themselves left very little in the way of records, and most symbols are interpreted by archaeologists and other scholars who study the symbols in context.

A general rule of thumb is: the shape of the design often determines the "meaning" of a knotwork design- triskele and trefoil shapes should be regarded as triskeles, bird, fish, and animal designs represent the attributes of the animal, etc. Circles represent unity or eternity, spirals reincarnation or cycles of life and rebirth, triangles and trefoils the threefold dominions of earth, sea, and sky. Squares or four-fold shapes are shield knots, symbols of protection from spirits or malevolent influence. Interlaced animals and men usually represent relationships, or emphasize the interdependence of mankind and nature.