What is Protection And Indemnity Insurance?

Legal Definition
Protection and indemnity insurance, more commonly known as "P&I" insurance, is a form of mutual maritime insurance provided by a P&I Club. Whereas a marine insurance company provides "hull and machinery" cover for shipowners, and cargo cover for cargo owners, a P&I Club provides cover for open-ended risks that traditional insurers are reluctant to insure. Typical P&I cover includes: a carrier's third-party risks for damage caused to cargo during carriage; war risks; and risks of environmental damage such as oil spills and pollution. In the UK, both traditional underwriters and P&I clubs are subject to the Marine Insurance Act 1906.

A P&I Club is a mutual insurance association that provides risk pooling, information and representation for its members. Unlike a marine insurance company, which reports to its shareholders, a P&I club reports only to its members. Originally, P&I Club members were typically shipowners, ship operators or demise charterers, but more recently freight forwarders and warehouse operators have been able to join.

Whereas the assured pays a premium to an underwriter for cover which lasts for a particular time (say, a year, or a voyage), a P&I Club member instead pays a "call". This is a sum of money that is put into the Club's pool, a kind of "kitty". If, at the end of the year, there are still funds in the pool, each member will pay a reduced call the following year; but if the Club has made a major payout (say, after an oil spillage) club members will immediately have to pay a further call to replenish the pool.

There is an International Group of P&I Clubs based at Peek House, London. These Clubs cooperate to provide funds in the event of huge claims using a complex system to determine liability.
-- Wikipedia
Legal Definition
This is insurance coverage that will cover any harm or damage that is done to a ship's crew and cargo due to negligence. It is carried by the owner of the ship.