Most of the students (and some of the faculty) I work with have no idea what a DOI is or why they should care. This is what I tell them.
A DOI – Digital Object Identifier – is like a social security number for a journal article. They can be applied to other digital items as well, but you are most likely to encounter them in scholarly articles.
A DOI normally consists of numbers, letters and other punctuation. It will look like this:
The DOI provides a way to permanently find a particular item. Publishers and scholarly societies change their websites all the time. Recently, a major publisher completely re-did their website, messing up all links into their site. I was quite annoyed. But the DOI could still link you to an article in a way that a URL couldn’t.
Incidentally, you can use the DOI to create a nice, neat compact URL for a journal article (instead of those really log URLs provided by some databases). You just need to add a little bit to the front of the DOI:
You can also use the DOI to quickly look up an article from your libraries homepage or this webpage.
To get a DOI, a publisher registers with a non-profit organization called CrossRef, and they work with the publisher to assign a unique number.
Increasingly, journals and citation styles are requiring authors to include DOIs in article citations where available.