Among molecular geneticists, the term stringency is frequently used to describe the conditions under which a target is exposed to the probe during hybridization. Depending upon the degree of homology between the probe and target sequences, high or low stringency conditions are applied.

• High stringency conditions, which include high hybridization temperatures and a low concentration of salt in the buffers, enable the hybridization of highly homologous nucleic acid sequences. When the conditions of stringency are too high, probes don’t bind to the target.
• Low stringency conditions, which include low hybridization temperatures and a high concentration of salt in the buffers, enables the hybridization of less homologous nucleic acid sequences. When the conditions of stringency are too low, probes bind to unrelated targets.