A felony, in many common law legal systems, is a serious crime; misdemeanors are less serious crimes. Originally, a felony was a crime for which the punishment was death or forfeiture of property. The distinction between a felony and misdemeanour has been abolished by many common law jurisdictions; see e.g. Crimes Act 1958 (Vic., Australia) s. 332B(1), Crimes Act 1900 (NSW., Australia) s. 580E(1). Other common law jurisdictions maintain the distinction, especially those in the United States. Those jurisdictions which have abolished the distinction generally adopt some other classification, e.g. in NSW, Australia, the crimes are divided into summary offences, minor indictable offences, and serious indictable offences. Many US jurisdictions which maintain the distinction between a felony and a misdemeanour divide felonies and misdemeanours into classes, e.g. class A felony, class B felony, etc.
In many jurisdictions in the United States a felony is any offence carrying a potential penalty of more than one year in prison, while a misdemeanour would carry a penalty of less than one year in prison. In Massachusetts, on the other hand, a felony is any offence which carries any prison time.