Gaelic football
Main article: History of Gaelic football
In the mid-19th century, various traditional football games, referred to collectively as caid, remained popular in Ireland, especially in County Kerry. One observer, Father W. Ferris, described two main forms of caid during this period: the "field game" in which the object was to put the ball through arch-like goals, formed from the boughs of two trees, and; the epic "cross-country game" which took up most of the daylight hours of a Sunday on which it was played, and was won by one team taking the ball across a parish boundary. "Wrestling", "holding" opposing players, and carrying the ball were all allowed.
By the 1870s, Rugby and Association football had started to become popular in Ireland. Trinity College, Dublin was an early stronghold of Rugby (see the Developments in the 1850s section, above). The rules of the English FA were being distributed widely. Traditional forms of caid had begun to give way to a "rough-and-tumble game" which allowed tripping.
There was no serious attempt to unify and codify Irish varieties of football, until the establishment of the Gaelic Athletic Association (GAA) in 1884. The GAA sought to promote traditional Irish sports, such as hurling and to reject imported games like Rugby and Association football. The first Gaelic football rules were drawn up by Maurice Davin and published in the United Ireland magazine on February 7, 1887. Davin's rules showed the influence of games such as hurling and a desire to formalise a distinctly Irish code of football. The prime example of this differentiation was the lack of an offside rule (an attribute which, for many years, was shared only by other Irish games like hurling, and by Australian rules football).

The split in Rugby football

An English cartoon from the 1890s lampooning the divide in rugby football which led to the formation of rugby league. The caricatures are of Rev. Frank Marshall, an arch-opponent of player payments, and James Miller, a long-time opponent of Marshall. The caption reads:Marshall: "Oh, fie, go away naughty boy, I don't play with boys who can’t afford to take a holiday for football any day they like!" Miller: "Yes, that’s just you to a T; you’d make it so that no lad whose father wasn’t a millionaire could play at all in a really good team. For my part I see no reason why the men who make the money shouldn’t have a share in the spending of it."
Further information: History of rugby league
The International Rugby Football Board (IRFB) was founded in 1886, but rifts were beginning to emerge in the code. Professionalism was beginning to creep into the various codes of football.
In England , by the 1890s, a long-standing Rugby Football Union ban on professional players was causing regional tensions within rugby football, as many players in northern England were working class and could not afford to take time off to train, travel, play and recover from injuries. This was not very different from what had occurred ten years earlier in soccer in Northern England but the authorities reacted very differently in the RFU, attempting to alienate the working class support in Northern England. In 1895, following a dispute about a player being paid broken time payments, which replaced wages lost as a result of playing rugby, representatives of the northern clubs met in Huddersfield to form the Northern Rugby Football Union (NRFU). The new body initially permitted only various types of player wage replacements. However, within two years, NRFU players could be paid, but they were required to have a job outside sport.
The demands of a professional league dictated that rugby had to become a better "spectator" sport. Within a few years the NRFU rules had started to diverge from the RFU, most notably with the abolition of the line-out. This was followed by the replacement of the ruck with the "play-the-ball ruck", which allowed a two-player ruck contest between the tackler at marker and the player tackled. Mauls were stopped once the ball carrier was held, being replaced by a play-the ball-ruck. The separate Lancashire and Yorkshire competitions of the NRFU merged in 1901, forming the Northern Rugby League, the first time the name rugby league was used officially in England.
Over time, the RFU form of rugby, played by clubs which remained members of national federations affiliated to the IRFB, became known as rugby union.

The globalisation of Association football
Main article: History of FIFA
The need for a single body to oversee Association football had become apparent by the beginning of the 20th century, with the increasing popularity of international fixtures. The English Football Association had chaired many discussions on setting up an international body, but was perceived as making no progress. It fell to associations from seven other European countries: France, Belgium, Denmark, Netherlands, Spain, Sweden, and Switzerland, to form an international association. The Fédération Internationale de Football Association (FIFA) was founded in Paris on May 21, 1904. Its first president was Robert Guérin. The French name and acronym has remained, even outside French-speaking countries.

The reform of American football
Both forms of rugby and American football were noted at the time for serious injuries, as well as the deaths of a significant number of players. By the early 20th century in the USA, this had resulted in national controversy and American football was banned by a number of colleges. Consequently, a series of meetings was held by 19 colleges in 1905–06. This occurred reputedly at the behest of President Theodore Roosevelt. He was considered a fancier of the game, but he threatened to ban it unless the rules were modified to reduce the numbers of deaths and disabilities. The meetings are now considered to be the origin of the National Collegiate Athletic Association.
One proposed change was a widening of the playing field. However, Harvard University had just built a concrete stadium and therefore objected to widening, instead proposing legalisation of the forward pass. The report of the meetings introduced many restrictions on tackling and two more divergences from rugby: the forward pass and the banning of mass formation plays. The changes did not immediately have the desired effect, and 33 American football players were killed during 1908 alone. However, the number of deaths and injuries did gradually decline.

Further divergence of the two rugby codes
Rugby league rules diverged significantly from rugby union in 1906, with the reduction of the team from 15 to 13 players. In 1907, a New Zealand professional rugby team toured Australia and Britain, receiving an enthusiastic response, and professional rugby leagues were launched in Australia the following year. However, the rules of professional games varied from one country to another, and negotiations between various national bodies were required to fix the exact rules for each international match. This situation endured until 1948, when at the instigation of the French league, the Rugby League International Federation (RLIF) was formed at a meeting in Bordeaux.
During the second half of 20th century, the rules changed further. In 1966, rugby league officials borrowed the American football concept of downs: a team could retain possession of the ball for no more than four tackles. The maximum number of tackles was later increased to six (in 1971), and in rugby league this became known as the six tackle rule.
With the advent of full-time professionals in the early 1990s, and the consequent speeding up of the game, the five metre off-side distance between the two teams became 10 metres, and the replacement rule was superseded by various interchange rules, among other changes.
The laws of rugby union also changed significantly during the 20th century. In particular, goals from marks were abolished, kicks directly into touch from outside the 22 metre line were penalised, new laws were put in place to determine who had possession following an inconclusive ruck or maul, and the lifting of players in line-outs was legalised.
In 1995, rugby union became an "open" game, that is one which allowed professional players. Although the original dispute between the two codes has now disappeared — and despite the fact that officials from both forms of rugby football have sometimes mentioned the possibility of re-unification — the rules of both codes and their culture have diverged to such an extent that such an event is unlikely in the foreseeable future.

Football Today

Use of the word "football" in English-speaking countries
Further information: Football (word)
The word "football", when used in reference to a specific game can mean any one of those described above. Because of this, much friendly controversy has occurred over the term football, primarily because it is used in different ways in different parts of the English-speaking world. Most often, the word "football" is used to refer to the code of football that is considered dominant within a particular region. So, effectively, what the word "football" means usually depends on where one says it.
The name "soccer" (or "soccer football") was originally a slang abbreviation of association football and is now the prevailing term in the United States, Canada, Australia and New Zealand where other codes of football are dominant.
Of the 45 national FIFA affiliates in which English is an official or primary language, only three (Canada, Samoa and the United States) actually use "soccer" in their organizations' official names, while the rest use football (although the Samoan Federation actually uses both). However, in some countries, such as Australia and New Zealand, use of the word "football" by soccer bodies is a recent change and has been controversial. The governing body for Rugby Union in New Zealand changed its name from "New Zealand Rugby Football Union" to "New Zealand Rugby Union" in 2006.

Use of the word "football" in non-English