* Homogeneous Mixture: A mixture where the components are evenly distributed throughout. You can't visually distinguish the different parts.

* Heterogeneous Mixture: A mixture where the components are not evenly distributed. You can see distinct parts.

Saltwater is a solution where salt (NaCl) is dissolved in water (H2O). The salt molecules are spread evenly throughout the water, making it impossible to separate them by simple means. You can't see individual salt particles or distinct layers in saltwater.