A formulation is a mixture that has been designed as a useful product. It is made by mixing measured amounts of several components, each chosen for a particular job. Paints, fuels, cleaning products, medicines, fertilisers, foods and alloys are all formulations.
The amount of each component is carefully controlled, so the product always works the same way. A paint contains a pigment that gives it colour, a binder that makes it stick to the surface and a solvent that makes it easy to spread. A medicine contains an active ingredient plus other substances that make it safe and easy to take.
Alloys are formulations of metals. An alloy is a mixture of a metal with one or more other elements. It is a mixture, not a compound, because the elements are not chemically joined. Brass is an alloy of copper and zinc. Steel is an alloy of iron with a small amount of carbon.
Alloys are usually harder than pure metals. The atoms of the added element are a different size, so they stop the layers of atoms sliding over each other. This makes alloys more useful than pure metals for many jobs.
