A frontier is the political and geographical areas near or beyond a boundary. The term came from French in the fifteenth century, with the meaning "borderland"—the region of a country that fronts on another country (see additionally marches).
The word "frontier" additionally means a region at the edge of a settled area, especially in North American development. It is a transition zone where explorers, pioneers and settlers were arriving. A frontier can additionally be referred to as a "front". A difference has additionally been established in academic scholarship between Frontier and Border, the latter denoting a fixed, rigid and clear-cut form of state boundary. 
Frederick Jackson Turner said that "the significance of the frontier" was that as pioneers moved into the "frontier zone", they were changed by the encounter. For example, Turner argues that in the United States in 1893, unlimited free land in this zone was available, and thus offered the psychological sense of unlimited opportunity. This, in turn, had a large number of consequences such as optimism, future orientation, shedding of restraints due to land scarcity, and wasting of natural resources.
Colonial North America
In the earliest days of European settlement of the Atlantic coast, the frontier was essentially any part of the forested interior of the continent lying beyond the fringe of existing settlements along the coast and the great rivers, such as the St. Lawrence, Connecticut, Hudson, Delaware, Susquehanna River and James.
English, French, Spanish and Dutch patterns of expansion and settlement were quite different. Only a few thousand French migrated to Canada. These habitants settled in villages along the St. Lawrence river, building communities that remained stable for long stretches, rather than leapfrogging west the way the English and later Americans did. Although French fur traders ranged widely through the Great Lakes and Mississippi River watersheds, as far as the Rocky Mountains, they didn't usually settle down. Actual French settlement in these areas was limited to a few quite small villages on the lower Mississippi and in the Illinois Country. Likewise, the Dutch set up fur trading posts in the Hudson River valley, followed by large grants of land to patroons, who brought in tenant farmers that created compact, permanent villages. They didn't push westward.
In contrast, the English colonies generally pursued a more systematic policy of widespread settlement of the New World, for cultivation and exploitation of the land, which required the extension of European property rights to the new continent. The typical English settlements were quite compact and small—under 3 square km (1 square mile). Conflict with the Native Americans arose out of political issues, i.e. who would rule. Early frontier areas east of the Appalachian Mountains included the Connecticut River valley. The French and Indian Wars of the 1760s resulted in a complete victory for the British, who took over the French colonial territory west of the Appalachians to the Mississippi River. Americans began moving across the Appalachians into areas such the Ohio Country and the New River Valley.
Most of the frontier movement was east to west, but there were additional directions as well. The frontier in New England lay to the north; in Nevada to the east; in Florida to the south. Throughout American history, the expansion of settlement was largely from the east to the west, and thus the frontier is often identified with "the west". On the Pacific Coast, settlement moved eastward. In New England, it moved north.
Following the victory of the United States in the American Revolutionary War and the signing Treaty of Paris in 1783, the United States gained formal, if not actual, control of the British lands west of the Appalachians. Many thousands of settlers, typified by Daniel Boone, had already reached Kentucky, Tennessee, and adjacent areas. Some areas, such as the Virginia Military District and the Connecticut Western Reserve (both in Ohio), were used by the states as rewards to veterans of the war. How to formally include these new frontier areas into the nation was an important issue in the Continental Congress of the 1780s and was partly resolved by the Northwest Ordinance (1787). The Southwest Territory saw a similar pattern of settlement pressure.
For the next century, the expansion of the nation into these areas, as well as the subsequently acquired Louisiana Purchase, Oregon Country, and Mexican Cession, attracted hundreds of thousands of settlers. The question of whether the Kansas frontier would become "slave" or "free" was a spark of the American Civil War. In general before 1860, Northern Democrats promoted easy land ownership and Whigs and Southern Democrats resisted. The Southerners resisted Homestead Acts because it supported the growth of a free farmer population that might oppose slavery.
When the Republican Party came to power in 1860 they promoted a free land policy — notably the Homestead Act of 1862, coupled with railroad land grants that opened cheap (but not free) lands for settlers. In 1890, the frontier line had broken up (Census maps defined the frontier line as a line beyond which the population density was under 2 inhabitants per square mile or 0.8 inhabitants per square kilometre).
The American frontier was generally the most Western edge of settlements and typically more free-spirited in nature than the East because of its lack of social and political institutions. The idea that the frontier provided the core defining quality of the United States was elaborated by the historian Frederick Jackson Turner, who built his Frontier Thesis in 1893 around this notion. Subsequently, the frontier has additionally been described as the point of contact between two cultures, where contact led to exchanges that affected both cultures.
A "Canadian frontier thesis" was developed by Canadian historians Harold Adams Innis and J. M. S. Careless. They emphasised the relationship between the centre and periphery. Katerberg argues that "in Canada the imagined West must be understood in relation to the mythic power of the North." [Katerberg 2003] In Innis's 1930 work The Fur Trade in Canada, he expounded on what became known as the Laurentian thesis: that the most creative and major developments in Canadian history occurred in the metropolitan centres of central Canada and that the civilization of North America is the civilization of Europe. Innis considered place as critical in the development of the Canadian West and wrote of the importance of metropolitan areas, settlements, and indigenous people in the creation of markets. Turner and Innis continue to exert influence over the historiography of the American and Canadian Wests. The Quebec frontier showed little of the individualism or democracy that Turner ascribed to the American zone to the south. The Nova Scotia and Ontario frontiers were rather more democratic than the rest of Canada, but whether that was caused by the need to be self-reliant at the frontier itself, or the presence of large numbers of American immigrants is debated.
The Canadian political thinker Charles Blattberg has argued that such events ought to be seen as part of a process in which Canadians advanced a "border" as distinct from a "frontier" – from east to west. According to Blattberg, a border assumes a significantly sharper contrast between the civilised and the uncivilised since, unlike a frontier process, the civilising force isn't supposed to be shaped by that which it is civilizing. Blattberg criticises both the frontier and border "civilizing" processes.
The pattern of settlement of the Canadian prairies began in 1896, when the American prairie states had already achieved statehood. Pioneers then headed north to the " Last Best West ". Before settlers began to arrive, North-West Mounted Police were dispatched to the region. When settlers began to arrive, a system of law and order was already in place and the Dakota lawlessness for which the American "Wild West" was famed didn't occur in Canada. Before settlers arrived, the federal government additionally sent teams of negotiators to meet with the Native peoples of the region. In a series of treaties, the basis for peaceful relations was established and the long wars with the Natives that occurred in the United States largely didn't spread to Canada. Like their American counterparts, the Prairie provinces supported populist and democratic movements in the early twentieth century.
The term frontier was frequently used in colonial Australia in the meaning of country that borders the unknown or uncivilised, the boundary, border country, the borders of civilisation, or as the land that forms the furthest extent of what was frequently termed "the inside" or "settled" districts. The "outside" was another term frequently used in colonial Australia, this term seemingly covered not only the frontier but the districts beyond. Settlers at the frontier thus frequently referred to themselves as 'the outsiders' or 'outside residents' and the area in which they lived as "the outside districts". At times one might hear the "fronter" described as "the outside borders". However the term "frontier districts" was seemingly used predominantly in the early Australian colonial newspapers whenever dealing with skirmishes between black and white in northern New South Wales and Queensland, and in newspaper reports from South Africa, whereas it was seemingly not so commonly used when dealing with affairs in Victoria, South Australia and southern New South Wales. The use of the word "frontier" was thus frequently connected to descriptions of frontier violence, as in a letter printed in the Sydney Morning Herald in December 1850 which described murder and carnage at the northern frontier and calling for the protection of the settlers saying: "...nothing but a strong body of Native Police will restore and keep order in the frontier districts, and as the squatters are taxed for the purpose of such protection".
In the European Union, the frontier is the region beyond the expanding borders of the European Union itself. The E.U. has designated the countries surrounding it as part of the European Neighbourhood. This is a region of primarily less-developed countries, a large number of of which aspire to become part of the E.U. Current applicants include Turkey and a large number of small countries in the Balkans and South Caucasus. Romania and Bulgaria joined the E.U. in 2007. Proposals to admit Turkey have been debated but are now currently stalled, partly on the ground that Turkey is beyond Europe's historic frontier and it is yet to comply with the 35 point policy areas set out by the E.U. If all or most East European states become members, the frontier might be the boundaries with Russia and Turkey.