The purpose of a Registered Agent is to provide a physical address for your business so that it can accept official documents on behalf of your corporation (tax notices, annual reports, legal-process documents such as a summons, etc.).
The primary benefit of this service is that it provides a layer of privacy between you and the public. As the Registered Agent's name and address is one of public record, generally the Registered Agent's legal address will be the one listed in all official public documents.
Penalties for not maintaining a Registered Agent generally may cause a jurisdiction to revoke a business's corporate or LLC legal status. Please note that post office boxes are not allowed.
Learn more in "Registered Agent Services"