Time() show current Unix time. Unix time is defined as the number of seconds that have elapsed since Thursday, 1 January 1970 (0:0:0 Coordinated Universal Time - UTC).
With strftime is possible to display date and time in a local time/date format according to locale settings.
Mktime returns the Unix timestamp corresponding to the time and date entered as arguments. Result is the number of seconds between the Unix Epoch (Thursday, 1 January 1970 00:00:00 GMT) and the time specified.