Lubrication refers to a process that occurs within 10 to 30 seconds of a woman becoming sexually aroused in which the vascular engorgement of the tissues that lie beneath the vaginal wall produce a vaginal lubrication on the inner walls of the vagina. It can result from physical stimulation, such as during sexual foreplay, or from merely thinking about sexual activity. Lubrication is a preparatory process during sexual activity that significantly facilitates sexual intercourse by allowing greater ease of movement as the sex organs rub against each other and create friction.

In everyday language, this often is referred to as "getting wet," and it is a sign to both the female and the male of growing physical preparedness and desire for sexual contact. Females vary considerably in the quantity of lubricating fluid that is produced, with some women experiencing a type of sexual dysfunction that involves little or no mucus production. When women do not produce enough lubricating fluid, engaging in sexual contact is often uncomfortable or painful. Manual or oral stimulation of the vagina may assist in the production and release of lubricating fluid. Failure to produce lubrication may be a sign of an emotional or physical problem that is in need of professional intervention, although it may also signal a lack of interest in a particular partner.

Lack of lubrication tends to be a more common problem with aging, particularly during and after menopause. Estrogen replacement therapy often reduces the problem and helps to maintain the viability of the vagina as well. Women who are menopausal or postmenopausal and experience decreased lubrication may want to consult their physician or gynecologist to discuss estrogen replacement therapy and other treatment options.

It is possible to use artificial lubricants such as various commercially sold jellies and creams to assist in achieving adequate lubrication. Most health professionals recommend a water-based lubricant such as KY Jelly or Astroglide over a petroleum-based product such as Vaseline. Water-based lubricants are more easily absorbed by and are less irritating to the delicate tissues in and around the genitals. Individuals who engage in anal intercourse, in which the penis is inserted into the partner's anus, should use artificial lubrication because of the lack of lubricating glands in the anus. Many males also use artificial lubricants to facilitate masturbation.