A Digital Object Identifier, known as DOI, is an alphanumeric code and the international recognized standard for persistently identifying digital objects in a globally unique way. A DOI is a string of letters and numbers that can be used to make resources directly available to anyone over the internet. In contrast to a URL, which might change and lead to no result, with a persistent identifier a researcher can remain confident that a citation will always lead to the original information about that object, even if the location of that object changes. Adding a DOI into a footnote or reference in a publication allows readers to immediately identify and find the data used in the research.