A homogeneous mixture is composed of two or more substances
mixed together that does have a uniform composition. If we
removed samples of the mixture from different locations the
composition of the two samples would be identical. Also a
homogeneous mixture will remain homogeneous forever.
A homogeneous mixture contains two or more different
substances in the same phase, that is, the mixture is a single
phase.
All mixtures of gases are homogeneous. Homogeneous mixtures
can also be prepared when the components are liquids, liquid and
solids. Homogeneous solid mixtures are difficult to prepare.
Solution is another term used to mean a homogeneous mixture.
An aqueous solution of sodium chloride would be a homogeneous
mixture of sodium chloride and water. We would not say a solution
of water and gasoline, because those two components do not form a
homogeneous mixture.