Hybridization is the process of binding complementary pairs of DNA molecules. A DNA molecule has a very strong preference for its sequence complement, so just mixing complementary sequences is enough to induce them to hybridize. Hybridization is temperature dependent, so DNAs that hybridize strongly at low temperature can be temporarily separated (denatured) by heating.
Reference: http://www.cs.wustl.edu/~jbuhler/research/array/
