A solution is a homogeneous mixture. Homogeneous means it consists of one phase. Within a phase, sampling the composition in one physical region gives the same outcome as does sampling somewhere else in the same phase.

In a dilute solution, we usually speak of two components -- the solvent, and the solute. The solvent is the component that can be thought of as doing the dissolving, or bringing about the dissolving. It is the component in largest amount. The solute is the component that becomes dissolved. A typical submicroscopic mental model is that, inside the solution, solute molecules are far apart from one another. Solvent molecules, on the other hand, are shoulder to shoulder. The solute molecules would be surrounded by solvent molecules.

With the solvent, molecules are attracted to one another. Likewise, solute molecules are attracted to one another. In the solution, both solvent and solute molecules trade interactions with one another for different interactions. The new interactions may be stronger than before solution formation. To some degree, they also may be weaker than before solution formation.