Media playback is unsupported on your device NHS Health Check: What's causing hospital delays?
5 February 2017 Last updated at 14:31 GMT
The NHS is under unprecedented pressure. Demand is rising and hospitals, in particular, are struggling to cope.
But how exactly do patients flow round the system and what happens to hospitals when they cannot cope?
The BBC has produced an animated video to help you understand more about the health service and the strain it is under.