Fasting is primarily a movement of willing abstinence or reduction from some or all food, drink, or both, for a period of time. An absolute fast (dry fasting or respirationism) is normally defined as abstinence from all food and liquid for a defined period, usually a period of 24 hours, or a number of days. Water fasting allows drinking water but nothing else. Other fasts may be only partially restrictive, limiting particular foods or substances. The fast may also be intermittent in nature. Fasting practices may preclude intercourse and other activities as well as food.