Your resting heart rate is how many times your heart beats per minute when you are awake, calm and still. Most adults sit somewhere between 60 and 100, and very fit people can be lower. That range is wide on purpose, so where you land in it says little. What is far more useful is your own usual number and how far today's reading wanders from it.
Below is a week of morning readings. Drag any dot up or down to change that day, then drag the last dot, "Today", and see where it falls against your usual band. The starting values are made up; replace them with yours.
Several things push your morning reading up for a day or two, and none of them mean something is wrong with your heart.
Over the long run, regular endurance training tends to lower resting heart rate, as the heart pumps more blood with each beat. For most beginners the change is a few beats over a few months, not a dramatic drop, and it varies a lot between people.
The trick is consistency, not precision. Take it at the same time each day, ideally soon after you wake up and before coffee, sitting or lying still for a minute or two first.
Wrist sensors can drift when the strap is loose or your skin is cold, so treat a single odd reading with suspicion and look at the trend instead.
This guide is not medical advice, and a watch cannot diagnose anything. Talk to a doctor if your resting heart rate is regularly above 100, or regularly below 60 when you are not a trained athlete. Seek help promptly if a fast or slow heartbeat comes with fainting, dizziness, chest pain or shortness of breath. If you take heart medication, are pregnant, or have a heart condition, follow your doctor's advice rather than a band's.
The band is a simple rule of thumb for healthy adults tracking their own trend. It is not a screening test, and it will not suit anyone whose heartbeat is irregular or who has been told to monitor their heart rate for medical reasons.