“1933 Act” is the Securities Act of 1933, as amended.  In general, the 1933 Act applies to all Securities offerings in the U.S., and all Issuers of Securities in the U.S. (including Privately-Held Companies and Public Companies) must either register their transaction under, or secure an exemption from the registration requirements of, the 1933 Act.

For example, in a typical Venture Capital Financing, it is typical and prudent for the Issuer to secure an exemption from registration and comply with the “safe harbor” disclosure and filing requirements of Regulation D (which is part of the 1933 Act).