Gray literature is a catchall category for information published by other than conventional means (e.g., books and journal articles). Often such literature lacks a formal publisher, making it difficult to find in library databases. Gray literature includes theses and dissertations, conference papers, government publications, and industry white papers.
A white paper is "an authoritative report or guide that informs readers concisely about a complex issue and presents the issuing body's philosophy on the matter. It is meant to help readers understand an issue, solve a problem, or make a decision." White papers are one kind of gray literature.
Gray literature may provide you with salient and important information on a topic, including industry statistics, company performance, business strategy, market analysis, and more. Finding gray literature depends on the nature of your project, but a good place to start is Google Scholar.
One way to locate gray literature is to identify organizations that represent or lobby on behalf of the company or industry you're researching. For instance, if you're looking for information on the outdoor recreation industry, you could google that phrase, which directs us to the
Once you've found a trade group like AORE, look for a 'Resources' or 'Publications' tab like this one:
Among other freely-available AORE publications is the group's annual report, which explains what "AORE has accomplished in a specific year, why we do what we do, and the impact we have on the outdoor recreation and education community."