It is a financial operation consisting in reducing the number of company's shares that can be traded on the Stock Exchange, without modifying the share capital of the company. It corresponds to an exchange of a certain number of the company's existing shares against a new share.
The account holder is the company or the agent named by the company to manage its registered accounts. With this kind of share, the company has access to information about the shareholder. If you manage your own securities, you are called a pure registered shareholder. If you entrust the management of the account to a financial intermediary, you are an administered registered shareholder.