Digital object identifiers, known as DOIs for short, offer a unique way to identify a digital object, such as a Web page, on-line journal article or Web file. A digital object has the same DOI for its existence, even if it moves from one web database to another, or modifies its form. To work with DOIs, you'll need to get a DOI link, or turn the unique number that identified the object into a URL that is accessible via Internet browsers. Not all pieces of information on the Internet have DOIs, but many do.
Look for a DOI number on your document. Most journals and Web pages denote the DOI number as "DOI:xxxx" where the "x" represents unique numbers or letters that make up the DOI. The DOI may be at the bottom of the Web page, in the abstract or in the article citation.
Use CrossRef's "Free DOI Lookup" to retrieve a DOI if you do not have the page in front of you (crossref.org). Enter the article name and the author's name to find matching DOIs. If you know the journal publishing the article, enter that as well. Press "Search" to find matching articles and get their DOI numbers. Alternately, if you have a citation and want to locate a DOI, copy and paste the citation directly into CrossRef's "Automatic parsing of a formatted reference" text box. Then press "Search" to get a DOI from a reference.
Copy down the DOI number once you have it, whether you retrieved it from the article or from CrossRef.
Add the following URL as a prefix to the DOI to make a DOI link: http://dx.doi.org/
For example, if you had a DOI that was "123a," its DOI link would be "http://dx.doi.org/123a."
Type the DOI link in your web browser's search bar to visit the DOI using the link.