Formally, the Regency time period in the United Kingdom is the period of time between 1811, when King George III was determined unable to rule and his son the Prince of Wales, later George IV, was installed as his proxy as Prince Regent; and 1820, when George IV became King on upon the death of his father.
The term called the Regency era is occasionally used to refer to a more extended time frame than the decade of the formal Regency. The period of time between 1795 and 1837 (the latter part of the reign of George III and the reigns of his sons George IV, as Prince Regent and King, and William IV) was characterized by distinctive trends in British architecture, writing, fashions, political relations, and culture.
The era was a time of excess for the aristocracy: for example, it was during this time that the Prince Regent built the Brighton Pavilion. However, it was also an period of uncertainty caused by several factors including the Napoleonic wars, intermittent riots, and the anxiety that the British people might simulate the upheavals of the French Revolution.
For modern readers, the Regency period provides an endless plethora of plots, characters and love interests. The Regency period as a genre was essentially created by Georgette Heyer in the early 1920s. Her books typifies the period, lifestyle and manners of the Regency. In my opinion, every modern Regency author owes Georgette Heyer a debt of gratitude for the world that was created.