Simplify the following text for a Grade 3 native English-speaking person.
Original: The application contains a description of how to make and use the invention that must provide sufficient detail for a person skilled in the art ( i.e. , the relevant area of technology ) to make and use the invention . In some countries there are requirements for providing specific information such as the usefulness of the invention , the best mode of performing the invention known to the inventor , or the technical problem or problems solved by the invention .
Simplified: The invention also has to be hard to make .