Two types of timers are illustrated. A counting timer which returns the number of milliseconds that have elapsed since Windows was started and a callback timer. The counting time is useful when you need stop watch type functionality - to time an operation and see how long it took. The callback timer works better in an event driven application since it gives you a way to generate a single or periodic event in you application. All timer functions are based on the Multimedia DLL - winmm.dll.
Resolution is the size of the slice time can be divided into.
This structure has two elements. One to hold the minimum resolution and one for the maximum. A call to the timeBeginPeriod API sets the resolution to use while a call to timeEndPeriod clears it. To start timing an operation you issue a call to timeGetTime which returns the time in milliseconds since Windows started. Remember this time.