Cornell University has a great online source called the Legal Information Institute that describes the Restatements as follows:
Restatements of the Law, aka Restatements, are a series of treatises that articulate the principles or rules for a specific area of law. They are secondary sources of law written and published by the American Law Institute (ALI) to clarify the law. Restatements currently exist for twenty areas of law such as Contracts.
The ALI created Restatements to help courts understand and interpret the current common law. Thus, Restatements synthesize and restate existing case law and statutes from various jurisdictions. Restatements contain the Black Letter, Comments, Illustrations, and Reporter’s Notes. While the Black Letter, Comments, and Illustrations are approved by the ALI and represent the ALI’s official position, Reporter’s Notes represent only the position of the reporter and not ALI. The Black Letter are the applicable legal rules, principles, or statements of law. Comments follow black letter rules; they explain the rule, its background and rationale for adoption, and how to apply the rule. Illustrations are part of Comments; they provide examples of how the Black Letter would be applied to a particular set of facts. Reporter’s Notes discuss the authority of the Black Letter. Reporters can also use the notes component to suggest related areas for investigation.
As secondary sources, Restatements are only a source of persuasive authority and do not replace precedents and controlling statutes. However, courts may choose to adopt or cite approvingly to Restatement provisions as law, thereby making that provision mandatory authority.
The Restatement of Contracts 2d is available in print in the Rinn Law Library and is also available on Westlaw. Once at the Westlaw Restatement of Contracts search page you can either type in the word or concept that you would like to learn more about or you can select the 2d and use the + sign to open the subsections such as: formation, statute of frauds, defenses, performance and non performance, and remedies.
This work is the quintessential guide to the modern common law of contracts. It covers fundamental principles, providing a complete, coherent overview of contract law. Relied on and adopted by courts nationwide, this authoritative work is one of ALI’s most frequently cited publications.
Volume 1 covers the meaning of terms; formation of contracts-parties and capacity; formation of contracts-mutual assent; formation of contracts-consideration; the Statute of Frauds; mistake; and misrepresentation, duress, and undue influence.
Volume 2 includes unenforceability on grounds of public policy; the scope of contractual obligations; performance and non-performance; impracticability of performance and frustration of purpose; discharge by assent of alteration; joint and several promisors and promisees; and contract beneficiaries.
Volume 3 deals with assignment and delegation and remedies.