The eight trigrams, or bagua, are the three-line figures, each line broken or unbroken, that combine in pairs to form the sixty-four hexagrams of the I Ching. Each trigram has a name, a natural image (heaven, earth, thunder, water, mountain, wind, fire, lake), and a web of associations: a family member, a direction, a season, an element of the wu xing.
The eight are arranged in two classic sequences, the Earlier Heaven (Fu Xi) and Later Heaven (King Wen) orders, which place them differently around the compass and are used for different purposes in cosmology, divination and feng shui.