time conversions

[Chad A. Adlawan]

hello everyone !!!
  this is a non-debian specific question and i hope ull bear w/ me on this ...
  can someone suggest to me any nice documents re converting time for major 
timezones ?  UTC, PDT, PST (whatever those are), GMT, PHT (my timezone, the 
only one i know) ...
  thanks a lot ...
Chad