Patent prosecution describes the interaction between applicants and their representatives, and a patent office with regard to a patent, or an application for a patent. Broadly, patent prosecution can be split into pre-grant prosecution, which involves arguing before, and sometimes negotiation with, a patent office for the grant of a patent, and post-grant prosecution, which involves issues such as post-grant amendment and opposition. Patent prosecution is distinct from patent litigation, which describes legal action relating to the infringement of patents.