search the above subject on google, you will find all you need.
in plain english, tri-band: 900, 1800 and 1900 MHz, US is 1800, China is 1900. GSM: the protocol supported in China. unlocked: most carriers lock their phones so you can only use within their network, you need to unlock the phone in order to use with any carriers.
once you step out the airplane in China, buy any SIM card and plug in, you are connected on the spot!
