Stockholders of Delaware corporations have a right to certain information concerning their holdings, even from private companies. Stockholders must be given prompt notice of any action of stockholders which they would have been entitled to vote upon. Furthermore, stockholders have a right to request access to the company's "books and records".
The right of stockholders to receive notice of stockholder actions generally refers in private companies to actions taken by the written consent of stockholders. If a company did not reach out to all of its stockholders who would have been entitled to participate in a vote on the matters addressed in such written consent for their approval, by statute the company must promptly let all of its stockholders know of such action.
In order to access a company's books and records, a stockholder must make a formal request to review the company's books and records, and such request must have been made for a "proper purpose". Companies rarely make their "books and records" available to their stockholders without such a request. Many stockholders waive their rights to review the company's books and records in connection with their purchase of their shares (for instance, the Investors' Rights Agreement published by the National Venture Capital Association includes an optional provision waiving this right).
What counts as being part of the "books and records" of a company is not clearly defined by statute, but Delaware courts have generally interpreted it to mean minutes of meetings of the board of directors and other formal presentations given to a company's board of directors.