Patent insurance is a protection against infringement of patents and the costs associated with it. Patent insurance is of two types: Patent Liability Insurance and Patent Pursuance Insurance. Patent Liability Insurance is a defensive instrument, which helps the insured fight an infringement lawsuit filed by a rival company. It is also called 'Patent Infringement Defense Insurance'. In this case, the insurance company pays a part of the legal expenses incurred and/or the damages to be paid. Patent Pursuance Insurance on the other hand, is an offensive instrument, which aids the insured fight against a patent infringing company. This is also called the 'Patent Enforcement Insurance' or 'Offensive Patent Insurance'. In this case, the insurer pays a portion of the legal expenses incurred by the insured company.