This session will provide a primer on the DOI (digital object identifier). To scholarly and professional publishers "link rot" is more than just an irritant--it's a serious challenge to the very value of publishing. In the 1990s, when publishers were looking to move content online, they needed a mechanism to ensure that links were persistent over the long term. To this end they created CrossRef--a self-sustaining organization that provides persistent reference linking to over 25 million citable digital objects including articles, books, media, and datasets. Amy Brand will explain why the CrossRef model works so well with DOIs, and describe how it is now being leveraged to address other challenges that publishers are currently facing.