Erotic lactation is when an individual is sexually aroused by breastfeeding or sucking on a woman's breasts. Those who engage in this sexual fetish often define their practice as being involved in an adult nursing relationship (ANR). The female breast and nipple is often viewed as important for sexual activity. So, it is not uncommon for oral and physical stimulation of the breasts to transform into breastfeeding. From a psychological perspective, erotic lactation can also be a form of an individual fulfilling both emotional and physical sexual desire. In lesbian relationships, mutual breastfeeding is often seen as a sign of affection.