In the history of the United Kingdom, the Victorian era was the period of Queen Victoria's reign, from 20 June 1837 until her death on 22 January 1901. The era followed the Georgian period and preceded the Edwardian period, and its later half overlaps with the first part of the Belle Époque era of Continental Europe. In terms of moral sensibilities and political reforms, this period began with the passage of the Reform Act 1832. There was a strong religious drive for higher moral standards led by the nonconformist churches, such as the Methodist, and the Evangelical wing of the established Church of England. Britain's relations with the other Great Powers were driven by the colonial antagonism of the Great Game with Russia, climaxing during the Crimean War; a Pax Britannica of international free trade was maintained by the country's naval and industrial supremacy. Britain embarked on global imperial expansion, particularly in Asia and Africa, which made the British Empire the largest empire in history. National self-confidence peaked.
Ideologically, the Victorian era witnessed resistance to the rationalism that defined the Georgian period and an increasing turn towards romanticism and even mysticism with regard to religion, social values, and arts.
Domestically, the political agenda was increasingly liberal, with a number of shifts in the direction of gradual political reform, industrial reform, and the widening of the franchise. There were unprecedented demographic changes: the population of England and Wales almost doubled from 16.8 million in 1851 to 30.5 million in 1901, and Scotland's population also rose rapidly, from 2.8 million in 1851 to 4.4 million in 1901. However, Ireland's population decreased sharply, from 8.2 million in 1841 to less than 4.5 million in 1901, mostly due to emigration and the Great Famine. Between 1837 and 1901 about 15 million emigrated from Great Britain, mostly to the United States, Canada, South Africa, New Zealand, and Australia.
In the strictest sense, the Victorian era covers the duration of Victoria's reign as Queen of the United Kingdom of Great Britain and Ireland, from her accession on 20 June 1837—after the death of her uncle, William IV—until her death on 22 January 1901, after which she was succeeded by her eldest son, Edward VII. Her reign lasted for 63 years and seven months, a longer period than any of her predecessors. The term 'Victorian' was in contemporaneous usage to describe the era. The era has also been understood in a more extensive sense as a period that possessed sensibilities and characteristics distinct from the periods adjacent to it, in which case it is sometimes dated to begin before Victoria's accession—typically from the passage of or agitation for (during the 1830s) the Reform Act 1832, which introduced a wide-ranging change to the electoral system of England and Wales. Definitions that purport a distinct sensibility or politics to the era have also created scepticism about the worth of the label "Victorian", though there have also been defences of it.
Michael Sadleir was insistent that "in truth the Victorian period is three periods, and not one". He distinguished early Victorianism – the socially and politically unsettled period from 1837 to 1850 – and late Victorianism (from 1880 onwards), with its new waves of aestheticism and imperialism, from the Victorian heyday: mid-Victorianism, 1851 to 1879. He saw the latter period as characterised by a distinctive mixture of prosperity, domestic prudery, and complacency – what G. M. Trevelyan similarly called the "mid-Victorian decades of quiet politics and roaring prosperity".