A gene symbol is a short-form abbreviation for a particular gene. Gene nomenclature rules were established by the Nomenclature Committee of the Human Genome Organisation (HUGO) and were later adopted by other species-specific research communities. Although HUGO assigns every known human gene its own "long" name, they also assign the gene a "short" symbol. In general, they require that gene symbols:

• are unique
• contain only Latin letters and Arabic numerals (0, 1, 2, ...)
• do not contain punctuation
• do not contain any reference to the species they are encoded in (i.e., "H/h" for humans)

For two examples of gene symbols, the gene "alcohol dehydrogenase" in Drosophila melanogaster has the symbol Adh, and DNA polymerase gamma in Homo sapiens has the symbol POLG.