The term "heterogeneous" refers to a mixture or system that consists of different components or elements. In a heterogeneous mixture, the individual parts can be easily distinguished and are not uniform throughout. For example, a salad is a heterogeneous mixture because you can see and identify the different ingredients like lettuce, tomatoes, and cucumbers. In contrast to homogeneous mixtures, where the composition is uniform, heterogeneous mixtures can vary in appearance and properties. Common examples include soil, concrete, and oil and water mixtures, where the distinct components retain their individual characteristics and can often be separated by physical means.