Each trigram is based on a series of the following two lines:

The broken line is Yin. The solid long line is Yang. Each trigram is named for a natural feature:

Trigram-EarthEarth (aka Plains, Meadow, Ground)-Key words: accepting, receptive, relaxing. The Earth is the Mother. She is maternal, long-suffering, devoted, tranquil, yielding, humble, careful, frugal, oppressed, and represents peaceful labor. Her number is 0 and her color is black.
Trigram-ThunderThunder (aka Air, Electricity, Lightning)-Key Words: stiumulating, arousing, exciting. Thunder is energetic, inspired, decisive, vital, vehement, rushed and volatile. It is action, passion, and being taken by surprise. Everything is fresh and new Its number is 1 and its color is a vibrant shade of red.
Trigram-RiverRiver (aka Water, Rain, Moon)-Key Words: independent, separate, self-reliant. Water is tenacious, diligent, relentless, enduring, lonely, melancholic, secretive, hard-working and resolute. Blood, sweat and tears. The depth of character to endure hard times. Its number is 2 and its color is a midnight shade of blue.
Trigram-LakeLake (aka Marsh, Cave, Valley)-Key Words: expressive, malleable, tolerant. The Lake is joyous, delighted, evocative, lusty, indulgent and obsessive. Unfulfilled desire. Lust and litigation. Arguments. Its number is 3 and its color is golden yellow.
Trigram-MountainMountain (aka Hill, Rock)-Key Words: grounded, stable, firm. The Mountain is restrained, sincere, still, lazy, miserly, stubborn, unchanging, and maintaining. Hoarding, guarding, and keeping. Retreat, attainment and completion. Its number is 4 and its color is a rich purple.
Trigram-FireFire (aka the Sun, the Hearth)-Key Words: reliance, cooperation, joining. The Fire is brilliant, illuminating, perceptive, beautiful, enthusiastic, fierce, violent, clinging, attached, and dependent. Flamboyant and ferocious. Its number is 5 and its color is a fiery orange.
Trigram-TreeTree (aka Wood, Wind)-Key Words: permeating, penetrating, insightful. The Tree if flexible, flowing, searching, indecisive, and confused. Either calm and even in a breeze, or gusty and uncertain in a gale. Its number is 6 and its color is a living green.
Trigram-HeavenSky (aka Heavens, Light)-Key Words: creating, challenging, powerful. The Sky is potent, expansive, decisive, arrogant, and proud. Creative, active, moving, and confrontational. Its number is 7 and its color is a blinding white.

So all these trigrams combine to form the 64 hexagrams (8 x 8 = 64). Know the essential meanings of these eight trigrams and you can make an educated guess at what a hexagram means. But still, each hexagram needs some explaining. So on to  some brief explantions of…