This Practice Note sets out essential concepts relating to professional indemnity insurance, including the types of losses covered, its practical operation and the nature of ‘claims made’ insurance. It also considers common policy terms, such as ‘any one claim’ and ‘in the aggregate’ in relation to the policy limit of indemnity and the application of the policy excess. Additionally, this Practice Note provides guidance on standard practices in the professional indemnity insurance market, covering key clauses such as the insuring clause, warranties and conditions and typical exclusions—including those for claims arising from acts or omissions occurring before the retroactive date. This Practice Note also covers insurers’ rights of subrogation and explains the purpose of run-off cover in this context.