Suspension is when particles of solid material are held within a fluid. The particles are large enough to not dissolve in the fluid, and they separate easily when disturbed. Particles may settle to the bottom of the container when left undisturbed.
A mixture similar to a suspension is a colloid. In a colloid, the solid particles remain suspended and do not settle even when left undisturbed. Colloids are an intermediate step between suspensions and solutions. Solutions are mixtures where the solid particles dissolve in the fluid and the two materials become one substance. These terms are typically used in chemistry settings during experiments to specify how a mixture should behave.