The FA Cup (Football Association Challenge Cup) is the oldest existing football competition in the world. It is the oldest among all tournaments as well as all leagues which still exist today. The first edition of Football Association Challenge Cup (FA Cup) was held in the 1871-1872 season. It has been held once a year ever since (with the exception of the interruptions caused during the first and the second World War). The Cup was first initially contested by twelve British teams (although several teams would refrain due to the travel costs). In the beginning, the FA Cup also included Scottish and Welsh clubs.
The first FA Cup matches ever, four on the same day, were played on 11 November 1871. The first final was played the following spring at the Kensington Oval, in which Wanderers defeated Royal Engineers 1-0.
Wanderers would also win the following edition, but they were helped in the second season by the rule which stipulated that the current champions were directly qualified for the final (the rule was abandoned after that tournament).
More and more teams participated in the subsequent years. Over 40 teams entered the competition in 1877 and over 50 in 1879. The 1879-1880 edition also involved several clubs known by the modern audience, such as Aston Villa, Blackburn Rovers and Nottingham Forest. In the 1883-1884 season, the tournament reached 100 registered teams. By this time, the professional era began and the amateur teams would soon be outpaced. A shift which would lead to the creation of the FA Amateur Cup in 1893.
The FA Cup was once the biggest sporting event in the world. The final which was played at Crystal Palace in 1913 gathered 121,000 people. The attendance was a world record at the time. In those days the stadiums were not build to hold that amount of people. Therefore, many stood in rows at the field between the stands with bad views of the action.
In 1923, when the final was played at Wembley for the first time, the attendance was even bigger. There is no official figure, but it has been estimated to around 200,000!
The FA Cup final is for many football fans associated with Wembley Stadium. This is an old tradition: Wembley has been the venue for the final since 1924 (with the exceptions of the interruption which took place between 2001 and 2006 when the stadium was renovated and Millenium Stadium served as venue for the final). Before Wembley came to be the choice for the final, Crystal Palace was for many years (1895-1914) the venue for the final. And before that it was Kensington Oval (with one exception in 1873 when the final took place at Lillie Bridge).
Source Information: https://www.footballhistory.org/tournament/fa-cup.html