A registration office commonly refers to a government agency that files compulsory information in the public interest.
The most common type of a registration office is a companies registration office or a trade register office. In most countries, the trade and company register is freely accessible (list of company registers). Additional commerce registers include patent registers and trademark registers (e.g. U.S. Patent and Trademark Office).
In countries with compulsory resident registration the term registration office is commonly short for resident registration office (e.g. German Meldeamt is short for Einwohnermeldeamt). Additional resident registers include civil registration offices (for birth and marriage) and immigration offices. Access to these registries is often limited, with information being publicly available only in the form of statistical overviews.
There exist a multitude of registers and relevant offices that are incorporated by the government to allow for taxation and to monitor regulations. In some countries, the management of these register databases is handled by a separate agency or it is part of a larger body - e.g. aircraft registration or vehicle registration.