Alternative names for people from the United Kingdom include nicknames and terms, including affectionate ones, neutral ones, and derogatory ones to describe British people, and more specifically English, Welsh, Scottish and Northern Irish people.
Brit is a commonly used term in the United States and elsewhere, simply as a shortened form of "Briton."
An archaic form of "Briton," similar to "Brit", always much more used in North America than Britain itself, but even there, it is outdated. An equivalent of the word "Engländer", which is the German noun for "Englishman". The term was also used extensively in the British Raj and is still used extensively in the Indian Subcontinent.
The term is thought to have originated in the 1850s as "lime-juicer", and was later shortened to "limey". It was originally used as a derogatory word for sailors in the Royal Navy, because of the Royal Navy's practice since the beginning of the 19th century of adding lemon juice or lime juice to the sailors' daily ration of watered-down rum (known as grog), in order to prevent scurvy.
Eventually the term lost its naval connection and was used about British people in general. In the 1880s, it was used to refer to British immigrants in Australia, New Zealand and South Africa. Although the term may have been used earlier in the U.S. Navy as a slang word for a British sailor or a British warship, such usage is not documented until 1918. By 1925, its usage in American English had been extended to mean any Briton, and the expression was so commonly known that it was used in American newspaper headlines.
The terms Pommy, Pommie and Pom, in Australia, South Africa and New Zealand usually denotes an English person (or, less commonly, people from other parts of the UK). The Oxford Dictionary defines their use as "often derogatory" but after complaints to the Australian Advertising Standards Board regarding five advertisements poking fun at "Poms", the board ruled in 2006 that these words are inoffensive, in part because they are "largely used in playful or affectionate terms". The New Zealand Broadcasting Standards Authority made a similar ruling in 2010. Indeed, the BBC itself has used the phrase upon occasion.