A thermometer is a medical instrument used to measure body temperature. It typically features a glass or plastic tube filled with a liquid, often mercury or alcohol, that expands and rises in the tube as the temperature increases. The thermometer has calibrated markings along the side that indicate temperature in degrees Celsius (°C). In this particular thermometer, measurements range from 35°C to 42°C, which makes it suitable for human body temperature readings. The design is slim and elongated, allowing for easy handling and placement under the tongue, in the armpit, or rectally. The clear material of the thermometer allows for easy reading of the liquid level, providing a quick and reliable assessment of fever or normal temperature.