Colloids are one of the primary types of mixture. It is a type of mixture in which solid or liquid particles are dispersed uniformly throughout a gas, liquid or solid. Colloid particles maybe seen in a beam of light such as dust in air and a shaft of sunlight. Blood, whipped cream and fog are examples of colloids. To be classified as colloid, the substance in dispersed phase must be larger than the size of a molecule but smaller than what can be seen with the naked eye. The component typically present in a relatively small amount is called dispersed phase and the substance or solution throughout which particulate is dispersed is called the dispersion medium. Colloid creates a Tyndall effect, it is the effect of light scattering in colloidal dispersion, if no light is shown, then it is a true solution. This effect is used to determine whether a mixture is a true solution or a colloid. A colloid may be a mixture of one substance that may spread out evenly inside another substance. They may be in two different phases or states of matter. One substance can be the dispersion medium, such as water or gas. The other is kind of dispersed medium, sometimes called the 'internal phase'. This is never tiny solid particles. Otherwise, if the dispersion medium is a gas, then the internal phase may be either tiny particles or tiny droplets of a liquid.