Technical reports include research done by government, corporations, and educational agencies, in association with government agencies, or using federal funds. Tech reports provide information on processes, progress or resultys of projects, research, and activities of the organization or institution or department. They are described as being between books and journal articles, and because they are distributed by the organization and not by a publisher they are often referred to as "gray literature". These technical reports are not necessarily part of a peer-review process.
"The primary function of a technical report is usually to give an official statement of research findings to sponsors or employers, such as the federal government. When the government performs or sponsors research, they may require as a part of the contract that reports of the research be published as a way to maintain public disclosure." borrowed from University of Washington --
Three categories of technical reports are:
Some examples of technical reports are NASA Technical Memorandum or Jet Propulsion Laboratory Technical Reports.