The term "grey literature" comes from the uncertainty of the status of this information. However, in cases where there may not be much information on a topic in peer-reviewed research, grey literature may prove a very valuable source of information and introduce alternate viewpoints.

Grey literature is literature produced by government, academics, business and industry in print and electronic formats, but which is not controlled by commercial publishers.  A full list of Document Types in Grey Literature is provided by GreyNet International. 

The most common type of grey literature you may come across at TSTC are:

• conference papers and proceedings
• reports (such as white papers, working papers, internal documentation)
• government documents
• technical notes and specifications
• proposals
• datasets/statistics
• patents
• unpublished trial data
• regulatory data
• speeches
• urban plans
• company information
• social media

Additional benefits to using grey literature include:

• Grey literature can be published much more quickly since it does not have to be subjected to the lengthy peer-review process. Results of studies may appear in grey literature 12 to 18 months before being published via traditional channels.
• Online information from organizations may be updated more frequently than traditional published journals/books.
• Some grey literature may contain more depth—for example, a dissertation may include some raw data not published in a journal article that author goes on to write.
• Grey literature may provide a broader overview of an issue/topic, such as a white paper or fact sheet.
• Minimizes reporting or publication biases; grey literature is more likely to include negative results - e.g. clinical trials.