Securities registration has two distinct meanings in finance. The first is regulatory: before securities can be offered to the public, the issuer must file a registration document with the securities regulator, setting out its business, finances and the terms of the offer. In the United States this is a registration statement filed with the Securities and Exchange Commission under the Securities Act of 1933, which includes the prospectus; frequent issuers may use shelf registration. Offers that qualify for an exemption, such as a private placement, do not need to be registered.
The second meaning is operational: entering the name of a security's owner in the issuer's records. For registered shares this is the share register, maintained by a registrar or transfer agent. Registration in this sense determines who receives dividends, notices and voting rights. Holdings are often registered in the name of a nominee or depository on behalf of the underlying investors.