Crossref.org's CrossRef, Ghent University's ExLibris's OpenURL 0.1, and OhioLink's/OSDN's OLinks are highlighted in a discussion of information linking and its benefits for librarians and other information professionals. The OpenURL framework, a Web-based protocol, permits standardized transmission of metadata. Implementation is through link resolvers, which helps meet the needs of each researcher, who may or many not need, for instance, the same full-text journal article that is of use to another researcher. CrossRef, which on its Web site is described as 'the citation linking backbone-a collaborative reference linking service that allows the user to click on a citation and be taken directly to the target content,' is a service of the Publishers International Linking Association (PILA). OpenURL/link resolver and CrossRef/DOI work in tandem; because OpenURL uses a link resolver such as SFX to address the suitable copy issue intrinsic in CrossRef. In addition, if a publisher does not have a proprietary link-to syntax that eases linking from a link resolver to an article, article-level linkage could still be possible via an article DOI. Therefore, the Open URL/link resolver and CrossRef/DOI can be compatible and complementary services for libraries, if the library has a link resolver service. Topics covered include the technology and operation of OpenURL 1.0; home- grown linking solutions; vendor-provided linking solutions; and the future of linking, which will include standardized authentication.