A vascular birthmark is a discoloration of the skin that is caused by blood vessels that don't form correctly. They are present at birth or appear shortly after birth. There are three major types of vascular birthmarks: Salmon patch (nevus simplex) is a flat patch of pink or red skin, often small, usually with poorly defined borders.
A thermometer is a device that measures temperature or temperature gradient using a variety of different principles. The word temperature comes from the Greek work thermo which is heat and meter to measure.
A typical thermometer is a calibrated, or numbered, glass tube that contains mercury. The silver mercury in the tube rises, or expands, when warmth of an object increases. The mercury falls when warmth of an object decreases. The calibrated scale on the tube of the thermometer allows us to read the temperature.