Digital Object Identifier
A typical use of a DOI is to give a scientific paper or article a unique number that can be used by anyone find the location of the paper. It may also make it possible to find an electronic copy, for example, on the Internet. The DOI system has a DOI resolution system which is used to locate where the document is. When the document is moved, the DOI resolution system is updated with the new location of the document.
For example, doi:10.1016/j.iheduc.2008.03.001 links to "Web 2.0 authorship: Issues of Referencing and citation for academic integrity" by Kathleen Gray et al. The work was published in The Internet and Higher Education, Vol. 11, Issue 2, 2008.