What is a solution? Are all mixtures solutions? Are all solutions mixtures?

A solution is a homogeneous mixture composed of only one phase (meaning they are made up of all liquid, all solid, or all gas). Not all mixtures are solutions, however, for there are also instances where there are more than one phase, such as heterogeneous mixtures.

A solution is when you have two or more substances (a solvent and solutes) mixed together, and you can't tell its components apart just by looking at it or under a microscope (it's homogeneous). All solutions are mixtures, but not all mixtures are solutions because mixtures can be heterogeneous.