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A solution is a homogeneous mixture of two or more components. The dissolving agent is the solvent. The substance which is dissolved is the solute. The components of a solution are atoms, ions, or molecules, which makes them 10^-9 m or smaller in diameter.

Example: Sugar and Water

Suspensions

The particles in suspensions are larger than those found in solutions. Components of a suspension can be evenly distributed by a mechanical means, like by shaking the contents, but the components will settle out.

Example: Oil and Water

Colloids

Particles intermediate in size between those found in solutions and suspensions can be mixed such that they remain evenly distributed without settling out. These particles range in size from 10^-8 to 10^-6 m in size and are termed colloidal particles or colloids. The mixture they form is called a colloidal dispersion. A colloidal dispersion consists of colloids in a dispersing medium.

Example: Milk

More Dispersions

Liquids, solids, and gases all may be mixed to form colloidal dispersions.

Aerosols: solid or liquid particles in a gas.
Examples: Smoke is a solid in a gas. Fog is a liquid in a gas.

Sols: solid particles in a liquid.
Example: Milk of Magnesia is a sol with solid magnesium hydroxide in water.

Emulsions: liquid particles in liquid.
Example: Mayonnaise is oil in water.

Gels: liquids in solid.
Examples: gelatin is protein in water. Quicksand is sand in water.

There is no link between fire and colloids.