The Georgian style is highly variable, but marked by symmetry and proportion based on the classical architecture of Greece and Rome, as revived in Renaissance architecture. Ornament is also normally in the classical tradition, but typically restrained, and sometimes almost completely absent on the exterior. The period brought the vocabulary of classical architecture to smaller and more modest buildings than had been the case before, replacing English vernacular architecture (or becoming the new vernacular style) for almost all new middle-class homes and public buildings by the end of the period.
Georgian architecture is characterized by its proportion and balance; simple mathematical ratios were used to determine the height of a window in relation to its width or the shape of a room as a double cube. Regularity, as with ashlar (uniformly cut) stonework, was strongly approved, imbuing symmetry and adherence to classical rules: the lack of symmetry, where Georgian additions were added to earlier structures remaining visible, was deeply felt as a flaw, at least before Nash began to introduce it in a variety of styles. Regularity of housefronts along a street was a desirable feature of Georgian town planning. Until the start of the Gothic Revival in the early 19th century, Georgian designs usually lay within the Classical orders of architecture and employed a decorative vocabulary derived from ancient Rome or Greece.
In towns, which expanded greatly during the period, landowners turned into property developers, and rows of identical terraced houses became the norm. Even the wealthy were persuaded to live in these in town, especially if provided with a square of garden in front of the house. There was an enormous amount of building in the period, all over the English-speaking world, and the standards of construction were generally high. Where they have not been demolished, large numbers of Georgian buildings have survived two centuries or more, and they still form large parts of the core of cities such as London, Edinburgh, Dublin, Newcastle upon Tyne and Bristol.
The period saw the growth of a distinct and trained architectural profession; before the mid-century "the high-sounding title, 'architect' was adopted by anyone who could get away with it". This contrasted with earlier styles, which were primarily disseminated among craftsmen through the direct experience of the apprenticeship system. But most buildings were still designed by builders and landlords together, and the wide spread of Georgian architecture, and the Georgian styles of design more generally, came from dissemination through pattern books and inexpensive suites of engravings. Authors such as the prolific William Halfpenny (active 1723–1755) published editions in America as well as Britain.
A similar phenomenon can be seen in the commonality of housing designs in Canada and the United States (though of a wider variety of styles) from the 19th century down to the 1950s, using pattern books drawn up by professional architects that were distributed by lumber companies and hardware stores to contractors and homebuilders.
From the mid-18th century, Georgian styles were assimilated into an architectural vernacular that became part and parcel of the training of every architect, designer, builder, carpenter, mason and plasterer, from Edinburgh to Maryland.
Georgian succeeded the English Baroque of Sir Christopher Wren, Sir John Vanbrugh, Thomas Archer, William Talman, and Nicholas Hawksmoor; this in fact continued into at least the 1720s, overlapping with a more restrained Georgian style. The architect James Gibbs was a transitional figure, his earlier buildings are Baroque, reflecting the time he spent in Rome in the early 18th century, but he adjusted his style after 1720. Major architects to promote the change in direction from baroque were Colen Campbell, author of the influential book Vitruvius Britannicus (1715–1725); Richard Boyle, 3rd Earl of Burlington and his protégé William Kent; Isaac Ware; Henry Flitcroft and the Venetian Giacomo Leoni, who spent most of his career in England.