A heterogenous mixture is a mixture that consists of many visibly different substances or phases. The three phases that may be in a heterogenous mixture include gas, solid, and liquid.
In contrast to a heterogenous mixture, there are also homogenous mixtures. These mixtures have the same uniform composition and appearance throughout their entire system. A completely homogenous mixture is known as a solution. The only thing that differentiates homogenous mixtures from heterogenous mixtures is the size of particles in the mixture. Large particles are often found in heterogenous mixtures, while small particles that are not visible to the human eye are seen in homogenous mixtures.