"The materials used for legal research are generally divided into two broad categories: primary sources and secondary sources. Primary sources are laws, orders, decisions, or regulations issued by a governmental entity or official, such as a court, legislature, or executive agency; the President; or a state governor. Secondary sources offer analysis, commentary, or a restatement of primary law and are used to help locate and explain primary sources of law. Secondary sources may influence a legal decision but do not have the controlling or binding authority of primary sources."
From: “Secondary Legal Resources | Law Library of Congress.” December 31, 2014. https://www.loc.gov/law/help/secondary-rsrcs.php.