This document discusses congenital pyloric stenosis, which is the most common cause of non-bilious vomiting in infants. It describes the condition as a thickening of the pyloric muscle that partially or completely blocks the stomach outlet. Key points include that it occurs in about 3 in 1000 live births, more commonly in white males, and the standard treatment is a pyloromyotomy surgery to cut the thickened pyloric muscle. The surgery has a low risk and is usually curative for resolving the vomiting symptoms.