A colloid is a type of mixture where fine particles are dispersed throughout a continuous medium, such as a liquid or gas, but do not settle out over time. The particles in a colloid are typically larger than those in a solution but smaller than those in a suspension, usually ranging from 1 nanometer to 1 micrometer in diameter. Common examples of colloids include milk, fog, and paint, where the dispersed particles can influence the properties of the mixture, such as its appearance and texture.