The term for the aggregation of molecules in solution is called a colloid or, in some contexts, a solution itself. In a colloid, one substance is dispersed evenly throughout another, forming a mixture that does not settle over time. Examples include milk and fog. Solutions, on the other hand, involve one substance dissolving into another, like salt in water. Understanding these terms is vital for studying various scientific fields, including chemistry and biology, as they relate to concentration, stability, and interactions among substances.