Candidiasis is usually caused by infection with the yeast Candida albicans.
Candida albicans is a normal commensal in the gastrointestinal tract, mouth and vagina but not on the skin.
Infection with yeasts is the most common identifiable cause of vaginitis and vaginal discharge. They are also a common cause of balanitis and balanoposthitis. Occasionally, and especially in women, candidiasis may cause onycholysis.