According to the Patent Act, an invention must be presented in the patent application in such a way that a person skilled in the art can understand it and carry it out. The problem being solved must be clearly defined and the solution presented in a way that it can be understood. All necessary features must be sufficiently described from the outset. This is because the original technical documents determine what is protected.

The description is usually structured as follows:

• Title
  The title should be a brief and precise technical definition of the subject-matter of the invention. It must not contain any made-up names or trade marks.
• Technical field
  The invention must be assigned to a technical field by the applicant.
• State of the art
  The applicant describes the technology known to him to the extent necessary for understanding the invention. This description can refer to published technical literature, such as patent specifications, for example.
• Purpose of the invention
  A technical problem is derived from the technical field and the state of the art (also known as the prior art). The invention must solve this problem.
• Short description of the invention
  It must be clearly evident how the purpose is solved by the invention. The essential features of the invention are briefly and concisely outlined in this description. In addition, the benefits of the invention in terms of the state of the art are highlighted.
• List of technical drawings
  If the technical documents contain technical drawings, these are listed in an index with a brief indication of what each drawing represents.
• Detailed description of the invention
  This part is often the most comprehensive. Here, at least one way in which the invention can be carried out must be demonstrated in such a way that a person skilled in the art can understand it. All of the features necessary for the invention must be disclosed. If special embodiments of the invention or additional applications are also to be protected, the corresponding additional features must be presented in the technical documents. This is usually done through examples that are illustrated with technical drawings. It is very helpful if the drawings have numbers that refer to the text.
  Patent applications for chemical substances must describe at least one example of manufacturing. In addition, the substance must be identifiable by means of physical data.

A precise and detailed description forms the basis for the legal interpretation of the patent claims.