The term is broad, and may include more drastic transformations, such as the reduction of ore to metal (for which see Refining (metallurgy)).
Gases and liquids can also be refined by extraction with a selective solvent that dissolves away either the substance of interest, or the unwanted impurities.
Many solids can be refined by growing crystals in a solution of the impure material; the regular structure of the crystal tends to favor the desired material and exclude other kinds of particles.
The use of silicon and other semiconductors in electronics depends on precise control of impurities.
The zone melting process developed by William Gardner Pfann was used to produce pure germanium, and subsequently float-zone silicon became available when Henry Theuerer of Bell Labs adapted Pfann's method to silicon.