Resting heart rate – or pulse rate – is number of times your heart beats per minute (bpm) when you aren't active. This can vary widely from person to person and anything between 60-100 bpm can be considered 'normal' levels of resting heart rate, according to the British Heart Foundation. Pulse rate varies throughout the day and tend to be the lowest at certain stages of sleep.
Athletes, especially endurance athletes, generally have a lower resting heart rate: young, healthy athletes can have a resting heart rate close to 40 bpm or even lower sometimes.  The emphasis is on 'young' and 'healthy' as overworking your body, especially after a certain age, can have a detrimental effect on cardiovascular health.