Theft is the act of taking another person's property or services without that person's permission or consent with the intent to deprive the rightful owner of it. The word theft is also used as a synonym or informal shorthand term for some crimes against property, such as larceny, robbery, embezzlement, extortion, blackmail, or receiving stolen property. In some jurisdictions, theft is considered to be synonymous with larceny, while in others, theft is defined more narrowly. Someone who carries out an act of theft may be described as a "thief" (plural: thieves).

Theft is the name of a statutory offense in California, Canada, England and Wales, Hong Kong, Northern Ireland, the Republic of Ireland, and the Australian states of South Australia and Victoria.

Elements.

The actus reus of theft is usually defined as an unauthorized taking, keeping, or using of another's property which must be accompanied by a mens rea of dishonesty and the intent to permanently deprive the owner or rightful possessor of that property or its use.

For example, if X goes to a restaurant and, by mistake, takes Y's scarf instead of her own, she has physically deprived Y of the use of the property (which is the actus reus) but the mistake prevents X from forming the mens rea (for example, because she believes that she is the owner, she is not dishonest and does not intend to deprive the "owner" of it) so no crime has been committed at this point. But if she realizes the mistake when she gets home and could return the scarf to Y, she will steal the scarf if she dishonestly keeps it (theft by finding). Note that there may be civil liability for the torts of trespass to chattels or conversion in either eventuality.

By jurisdiction.

The following are the countries with the most cases of theft, as well as the respective rates per 100,000 people, according to the United Nations in 2018.

United States.

In the United States, crimes must be prosecuted in the jurisdiction in which they occurred. Although federal and state jurisdiction may overlap, even when a criminal act violates both state and federal law, in most cases only the most serious offenses are prosecuted at the federal level.

The federal government has criminalized certain narrow categories of theft that directly affect federal agencies or interstate commerce. The Model Penal Code, promulgated by the American Law Institute to help state legislatures update and standardize their laws, includes categories of theft by unlawful taking or by unlawfully disposing of property, theft by deception (fraud), theft by extortion, theft by failure to take measures to return lost or mislaid or mistakenly delivered property, theft by receipt of stolen property, theft by failing to make agreed disposition of received funds, and theft of services.

Although many U.S. states have retained larceny as the primary offense, some have now adopted theft provisions.