Some notable Celtic symbols are the Irish harp, indicating the soul's eternal life, the shamrock, indicating luck and the claddagh, a symbol combining a heart, crown and hands to represent love, loyalty and friendship, respectively. The Irish harp once also symbolized Ireland, as one of the most popular Celtic instruments. Nowadays, it can be seen on Irish coins, official seals and uniforms and, perhaps more famously, as the logo for Guinness stout ale.
Knots are common Celtic symbols as well, and different styles have different meanings. Spirals, for example, which predated even the Celts as cave art, are thought to have represented the sun or, when doubled, the equinox. Maze and step patterns are considered indicative of the progression of life or time, or else the meeting of earthly and heavenly spheres of existence.
Birds have a similar symbolic significance in Celtic art and culture, acting as messengers between mortals and the gods. Other animals are also featured heavily in Celtic symbolism. The Celtic horse, for instance, represents victory in battle. The dragon, which became a symbol of Wales, represents fertility and power, while the Celtic serpent is symbolic of a cycle of rebirth, shedding its skin each year to continue living eternally. For Celts, dogs were a sign of honor and were gifted to deserving warriors or chieftains.