A pulse oximeter is a small, portable device that is used to measure the oxygen saturation level in the blood. It works by shining a light through the skin and detecting the amount of oxygen in the blood. This information is then displayed on the device's screen as a percentage. Pulse oximeters are commonly used in medical settings, but they can also be useful for individuals who have respiratory issues or who are monitoring their overall health. They are easy to use and can provide valuable information about oxygen levels in the blood in just a matter of seconds.