(credit: Ciaran McGuiggan) With the October 2015 deadline behind us and Square now offering a compatible reader, we're surfacing our explainer on the US' slow transition to the chip-and-PIN credit card system. This piece was originally posted in August 2014, but we've made some minor modifications to bring it up to date. Earlier this week, mobile payments company Square announced that it is finally launching its long-awaited card reader that will accept payments from cards with an embedded chip or a Near Field Communication (NFC) chip.