Vaginal secretions (or vaginal discharge) are produced in the vagina from two types of secretory glands. The mixture of these secretions forms a more or less liquid mucus, usually translucent with a slightly milky appearance, whose quantity and biochemical and microbial composition vary according to the time of the menstrual cycle and the state of health. The colour, thickness and odour of the vaginal fluids change according to the time of the menstrual cycle and the degree of sexual arousal (more or less depending on the woman and her age). At the time of ovulation the cervical mucus (produced by the glands near the cervix) becomes more liquid, which favours and accelerates the ascent of spermatozoa towards the tubes and the ovary, but the vaginal discharge becomes thicker and more viscous.

These secretions have four functions: self-cleaning of the vagina, immunisation against external agents, lubrication and facilitation of reproduction.