* Homogeneous Mixture: A mixture where the components are evenly distributed throughout the sample. You cannot visually distinguish the individual components.

* Heterogeneous Mixture: A mixture where the components are not evenly distributed. You can visually distinguish the individual components.

* Solution: A homogeneous mixture where one substance (solute) is dissolved in another (solvent).

In this case:

* NaCl (salt) is the solute, and it completely dissolves in the water.

* H2O (water) is the solvent.

Since the salt dissolves completely and evenly distributes throughout the water, resulting in a uniform composition, the sample is a homogeneous mixture, specifically a solution.