A heart rate monitor is a piece of electronic equipment that can be used to track your heart functions continuously. It allows people to monitor the impact that their exercise routine is having on their heart rate. Using the common formula of 220 less your age gives you a target. For example, if you are 30 years old, your exercise target should be a pulse of 190 beats per minute. The heart rate monitor lets you see your pulse in real time, thus allowing you to know when the target has been met.
Heart rate monitors are produced by the millions and designed to cater to specific types of individuals. Some heart monitors are primarily designed for weight loss programs while others are meant for the use of athletes or fitness programs. Some are wireless or come as a built-in feature of exercise equipment like a treadmill or an exercise bike. It can be strapped to your wrist or of considerable size. It may or may not emit any electromagnetic waves, depending on its purpose. A fetal heart monitor, for instance, must not produce any waves at all as this may affect the health of the baby.
This site, Monitor Your Heart Rate, specializes in the athletic types. Enjoy, but always make sure you discuss your exercise program with a medical professional. Heart rate monitors are not meant to replace medical professionals, but are a useful tool once you have establish plans and goals for your exercise program.