The transfer of possession of something (by the bailor) to another person (called the bailee) for some temporary purpose (eg. repair or storage) after which the property is either returned to the bailor or otherwise disposed of in accordance with the contract of bailment.
Lending your car or any other item of personal property is actually a bailment contract.
Bailment, as quoted in Petrifond v Midwest 1996 10 WWR 1 (Alberta Court of Appeal, citing Fridman's Law of Agency, 6th Ed.):
"... is the delivery or transfer of possession of a chattel (or other item of personal property) with a specific mandate which requires the identical (thing) either to be returned to the bailor or to be dealt with in a particular way by the bailee....
"(T)he bailee does not represent the bailor. He merely exercises, with the leave of the bailor (under contract or otherwise), certain powers of the bailor in respect of his property. (T)he bailee has no power to make contracts on the bailor's behalf; nor can he make the bailor liable, simply as bailor, for any acts he does."
Bailment implies, by definition, the return by the bailee of the goods or personal property; otherwise the contract would be one of sale.
And like elsewhere, as the common law employed judges and barristers to weave a perpetual quilt of jurisprudence, the law of bailment, as it were, has its own books and professors. One, published in 1901 by Wyatt Paine, has a title which sounds like the sequel to the movie Borat:
"Bailments: A Commentary on the Law of Custody and Possession As Distinguished From Property, in Chattels".
Commercial bailees, such as storage facilities and garages, will usually, but not always, qualify liability by contract. This is almost always the case in maritime law and the transportation industy which rely extensively on the law of bailment.
Judicially, bailment was defined most recently in North King Lodge Ltd. v. Gowlland Towing Ltd. 2004 BCSC 460:
"... eludes precise definition because the term covers a host of legal relationships which have as a common denominator only that one is in possession of another’s chattel. Possession is the salient feature....
"Judges and writers have more or less consistently treated bailment as an express or implied contract....
"Bailment has been defined as the delivery of personal chattels on trust, usually on a contract, express or implied, that the trust shall be executed and the chattels be delivered in either their original or an altered form as soon as the time for which they were bailed has elapsed. It is to be noted that the legal relationship of bailor and bailee can exist independently of a contract. It is created by the voluntary taking into custody of goods which are the property of another."