Eye color is determined by the amount and type of pigments in the iris, the colored part of the eye. The most common eye colors are brown, blue, green, and hazel. Brown eyes have the most melanin, making them the darkest, while blue eyes have less melanin, resulting in a lighter color. Genetics play a significant role in determining eye color, with multiple genes influencing the final outcome. Eye color can also change over time due to factors like age, lighting, and health. Rare colors, such as gray or amber, can occur but are less common in the general population.