A more thorough explanation:

A registration system is a type of patent system where an invention is granted patent protection upon registration, without undergoing an official examination process. In contrast, an examination system requires an official examination to determine if the invention is eligible for patent protection.

The United States used a registration system for patents from 1790 to 1793. During this time, inventors were able to obtain patent protection simply by registering their invention, without having to go through an examination process.

Another example of a registration system is the trademark registration process. When a company registers a trademark, they are granted protection for that trademark without an official examination process. This allows them to use the trademark exclusively and prevent others from using it without permission.

These examples illustrate how a registration system works by granting protection to an invention or trademark upon registration, without requiring an official examination process.