A colloid is a mixture where one phase is microscopically mixed within another phase. The table below gives examples for all the possible colloids.

Phase Gas Liquid Solid
Gas So far there are no known examples Liquid aerosol e.g. fog, mist Solid aerosol e.g. smoke
Liquid Foam e.g. shaving cream Emulsion e.g. milk, mayonnaise Sol e.g. blood
Solid Solid foam e.g. styrofoam Gel e.g. jelly Solid sol e.g. steel