Petechiae are small, pinpoint-sized red or purple spots that appear on the skin, mucous membranes, or inside the mouth due to minor bleeding from broken capillaries. They can result from various causes, including physical trauma, certain medical conditions, infections, or blood disorders. While often harmless, the presence of petechiae can sometimes indicate a more serious underlying health issue, so it's advisable to seek medical attention if they appear suddenly or in large numbers.