A simple dictionary definition of time is, “ the point or period when something occurs.” Time is when we do things. However, there are two different kinds of time: clock time and real time. In clock time, as the name suggests, all time passes equally 60 seconds in a minute, 60 minutes in an hour, 24 hours in a day and 365 days in a year. On your twenty first birthday, you will be exactly 21 years old, no more or on less.