The patent claims determine the scope of protection of a patent. The patent claims therefore represent the most important part of a patent. The drafting of the patent claims deserves the greatest attention, since inadequate wording can significantly reduce the possible scope of protection, and errors in claim drafting may no longer be correctable. It is important to understand how claims are to be interpreted. Patent claims are interpreted from the perspective of the notional person skilled in the art. This fictional expert derives the meaning of a claim based on several interpretive approaches. After filing with the patent office, the possibilities for amending patent claims are limited. In particular, it must be ensured that no “inadmissible extension” or “broadening of the scope of protection” occurs. This specialist book describes all of these phases: from drafting claims before filing with the patent office, to interpreting claims before patent offices and courts, and the options for amending an already filed claim during opposition, appeal, and nullity proceedings. The associated online course first explains the basic concepts of patents, trademarks, utility models, and design rights. It then offers detailed guidance on how to obtain a patent without an attorney.