But why do we burp?
Burps or belches are simply the sound of gas leaving your body.When eating, we are not just swallowing foods or liquids, we also swallow air at the same time. These air contain gases..and sometimes, they need to get out. Extra gases are forced to come out from the stomach to the esophagus and to the mouth as a burp.
Babies are also subject to accumulation of gas in the stomach while feeding, and this can cause considerable agitation and/or discomfort to the child unless it is burped. The act of burping an infant involves placing the child in a position conducive to gas expulsion (for example holding the infant up to the adult's shoulder, with the infant's stomach resting on the adult's chest) and then lightly patting it on the lower back so that he or she burps.
The Ins and outs of burping.http://www.kidzworld.com/article/756-the-ins-and-outs-of-burping
Why do I burped?http://kidshealth.org/kid/talk/yucky/burp.html