Minecraft wiki entry for Mac_Scripting_Tutorial, associated text: The time is recorded in Unix time, which gives us the number of seconds elapsed since 00:00 on 1 January 1970. At the end of the script, we'll store the Unix time in another variable, which will give us the number of seconds that the entire script took to run. Just recording the seconds makes the time math a lot easier—this way, we don't have to do multiple hour/minute/second conversions, since we're already working with seconds.