WIY – it is a radio frequency chip. with this in your card by some stores and gas stations all you need to do is hold your or wave your card near the reading device and it picks up the information. criminals buy these reading devices and can read cards from people in their vicinity. you can be shopping anywhere or even walking down the street and if your RFID chip is unprotected someone can steal your information.
I know many people in Monsey that have had their cards duplicated and either used or attempted to be used around the world (England, Canada, parts of the US where they were nowhere near).