It is easier to describe what Grey Literature is not than to describe fully what it is. Grey Literature is a category that includes media, resources, documents, data, etc. that was not produced by traditional academic or commercial publishing systems, which is often referred to as White Literature. More simply put, if a resource was not published in an scholarly journal it is likely considered Grey Literature. Unlike White Literature, Grey Literature is not peer reviewed and is not typically published in books or scholarly journals. In fact, most Grey Literature today is distributed via digital formats as PDFs, web pages, blog posts and multimedia content. There is not a requirement for authors of Grey Literature to have substantial experience in the field they are writing in, as with academic publishing, but the best Grey Literature is written by authors or organizations who are well-known experts in the field. Grey Literature is not always factual and not always nonfactual.; it is not required to be entirely professional or casual. There is a wide spectrum of Grey Literature!

As such, Grey Literature can be very useful. This type of literature actually makes up the bulk of the information produced and used every day. The following all qualify as Grey Literature: 

• A local government's report on the city's water quality
• The front page news story from a national news company***
• A engineering PhD candidate's Dissertation on keyword latency  
• The state government's crime statistics from the last year
• A pamphlet from the Forest Service on the history of a National Park
• A report from an international Non-Governmental Organization (NGO) on modern slavery
• A blog post from a well-known academic on a new theory concerning her field
• Tweets from protestors involved in the Arab Spring demonstrations 
• Court transcripts and other legal documents

All these items can be useful in research, but using, evaluating, and finding good Grey Literature can be a challenge. This guide is designed to help users understand and navigate the complexities of this special literature. 

***Some people do not consider news to be Grey Literature because it comes from a commercial publishing system but others do consider the news to be Grey Literature because it is not peer reviewed or necessarily written by experts in the field. This guide includes news media as Grey Literature because it is not peer-reviewed and it can be evaluated with the same methods as Grey Literature.

Scholarly sources (also referred to as academic, peer-reviewed, or refereed sources) are written by experts in a particular field and serve to keep others interested in that field up to date on the most recent research, findings, and news.
When a source has been peer-reviewed, it has undergone the review and scrutiny of a review board of colleagues in the author’s field. They evaluate this source as part of the body of research for a particular discipline and make recommendations regarding its publication in a journal, revisions prior to publication, or, in some cases, reject its publication.

In essence, when a work is scholarly and peer-reviewed, the work of evaluating a resource is done by the publisher and the user of the resource does not have to spend too much time evaluating it themselves. This is extremely useful to users as it ensures that the information we are using is factual. However, the process of Peer Review is far from perfect; it has its own set of biases and issues with diversity, it is a lengthy process and scholarly and peer-reviewed works are often expensive to access. To learn more about the peer-review process, please visit this Library Guide: "Peer Review: An Introduction". 

When resources are not peer-reviewed, this means that the work of evaluating the resources falls almost entirely on the user.  Grey literature is typically only reviewed for accuracy by their own organization and the process for doing so varies widely from organization to organization, if they have one at all. The users reading the information cannot be sure if anyone has reviewed the facts presented in grey literature and if the organizations' biases have distorted the facts.  

Keep in mind that not every document found in scholarly journals is peer-reviewed, "White" Literature. Many journals publish book reviews, letters from the editors, event notifications etc that are actually Grey Literature!