Penal transportation or simply transportation refers to the relocation of convicted criminals, or other persons regarded as undesirable, to a distant place, often a colony for a certain term; later, specifically established penal colonies became their destination. While the prisoners may have been released once the sentence was served, they generally didn't have the resources to get themselves back home.
England transported its convicts, political prisoners as well as prisoners of war from Scotland and Ireland to its overseas colonies in the Americas from the 1610s until early in the American Revolution in 1776, when transportation to America was temporarily suspended by the Criminal Law Act 1776 (16 Geo. 3 c.43). The practice would become mandated for use in Scotland consequent to an act in 1785, but remained used less than in England. Transportation on a large scale would resume with the departure of the First Fleet to Australia in 1787, and continue there until 1868.
France transported convicts to Devil's Island and New Caledonia, but their usage both started and ended at later times.
Banishment or forced exile from a polity or society has been used as a punishment since at least Ancient Roman times. It removed the offender from society, possibly permanently, but was seen as a more merciful or forgiving punishment than execution. From the earliest days of English colonial schemes, new settlements beyond the seas were seen as a way to alleviate domestic social problems of criminals and the poor, as well as to increase the colonial labour force, production and overall benefit of the realm.
Initially based on the royal prerogative of mercy, and later under English Law, transportation was an alternative sentence imposed for a felony; it was typically imposed for offences for which death was deemed too severe. By 1670, as new felonies were defined, the option of being sentenced to transportation was allowed. Forgery of a document, for example, was a capital crime until the 1820s, when the penalty was reduced to transportation. Depending on the crime, the sentence was imposed for life or for a set period of years. If imposed for a period of years, the offender was permitted to return home after serving out his time, but had to make his own way back. Many offenders thus stayed in the colony as free persons, and might obtain employment as jailers or other servants of the penal colony.