thetheory,developedby Michael Porter, that abusinesscan get anadvantageover othersimilarbusinessesin threeways, bycostleadership(= being alow-costproducer), bydifferentiation(=offeringproductsthat are different and that haveaddedvalueinrelationtoquality), or byfocus(=sellingto apartof amarketwithparticularneeds)