The　question　of　what　heats　the　solar　corona　remains　one　of　the　most　important　puzzles　in　solar　physics　and　astrophysics.　Here　we　report　Solar　Dynamics　Observatory　Atmospheric　Imaging　Assembly　observations　of　coronal　heating　by　the　interaction　between　emerging　active　regions　(EARs)　and　the　surrounding　quiet　Sun　(QS).　The　EARs　continuously　interact　with　the　surrounding　QS,　resulting　in　dark　ribbons　which　appear　at　the　boundary　of　the　EARs　and　the　QS.　The　dark　ribbons　visible　in　extreme-ultraviolet　wavelengths　propagate　away　from　the　EARs　with　speeds　of　a　few　km　s(-1).　The　regions　swept　by　the　dark　ribbons　are　brightening　afterward,　with　the　mean　temperature　increasing　by　one　quarter.　The　observational　findings　demonstrate　that　uninterrupted　magnetic　reconnection　between　EARs　and　the　QS　occurs.　When　the　EARs　develop,　the　reconnection　continues.　The　dark　ribbons　may　be　the　track　of　the　interface　between　the　reconnected　magnetic　fields　and　the　undisturbed　QS＇s　fields.　The　propagating　speed　of　the　dark　ribbons　reflects　the　reconnection　rate　and　is　consistent　with　our　numerical　simulation.　A　long-term　coronal　heating　which　occurs　in　turn　from　nearby　the　EARs　to　far　away　from　the　EARs　is　proposed.