Why is Italian salad dressing an example of heterogeneous mixture?

Italian salad dressing is considered a heterogeneous mixture because it consists of various ingredients, such as oil, vinegar, herbs, and spices, that do not fully blend together. When mixed, these components can separate over time, with oil floating on top of vinegar due to differences in density. This uneven distribution of ingredients means that the dressing's composition can vary in different parts of the mixture, characteristic of a heterogeneous mixture.