The three main parts are abstract, description and claims.
The abstract is a brief summary of the patent application that describes the general idea of ??the invention, as well as the functions and important features of the invention.
The main function of the description is to explain in detail the function, structure, principle, operating method, drawings, embodiments, etc. of the invention.
The claims list the requirements of the patent application and are also the most important part. They describe the actual scope of protection for the invention.