Stardates Explained - 20101203.2142

You don't understand the startdates?

Take, for example, 20101203.2142

Let me stick some spaces in some helpful places:

2010 12 03 . 21 42

That better?

20101203 means 3rd December 2010, and 2142 is in 24-hour clock format, IE 9:42PM

Stardates in the Star Trek universe work in an entirely different way. Wikipedia has a good explanation on how Stardates work.