Burping (also called belching and eructation) is the release of gas from the upper digestive tract (esophagus and stomach) of animals through the mouth. It is usually audible. For humans, burping can be caused by normal eating processes, or as a side effect of other medical conditions. In human cultures, there is a range of levels of social acceptance for burping. In some contexts and cultures, burping is acceptable, while in others it is offensive or unacceptable. Failure to burp can cause pain or other negative effects.