First-class cricket (which for this purpose includes all "important matches" played before 1895), along with historical single wicket and the modern limited overs forms of List A and Twenty20, is one of the highest standard forms of cricket. The origin of the term "first-class cricket" is unknown but it was used loosely before it acquired an official status, effective in 1895, following a meeting of leading English clubs in May 1894. Subsequently, at a meeting of the Imperial Cricket Conference (ICC) in May 1947, it was formally defined on a global basis. A significant omission of the ICC ruling was any attempt to define first-class cricket retrospectively. This has left historians, and especially statisticians, with the problem of how to categorise earlier matches, especially those played before 1895 in Great Britain. The solution put forward by the Association of Cricket Statisticians and Historians (ACS) is to classify all pre-1895 matches of a high standard as important matches.
Test cricket, although the highest standard of cricket, is statistically a form of first-class cricket, although the term "First-class" is commonly used to refer to domestic competition only. A player's first-class statistics include any performances in Test matches.
Before 1895, "first-class cricket" was a common term used loosely to suggest that a match had a high standard; adjectives like "great", "important" and "major" were also loosely applied to such matches. There was at the time no concept of what became Test cricket and so an international match would be called a first-class one, as would any match involving two senior county clubs. At the beginning of the 1860s, there were only four formally constituted county clubs: Sussex is the oldest, formed in 1839, and it had been followed by Kent, Nottinghamshire and Surrey. In the early 1860s, several more clubs were founded and questions began to be raised in the sporting press about which should be categorised as first-class, but there was considerable disagreement in the answers. In 1880, the Cricket Reporting Agency was founded. It acquired influence through the decade especially by association with Wisden Cricketers' Almanack (Wisden) and the press came to generally rely on its information and opinions.
The term acquired official status, though limited to matches in Great Britain, following a meeting at Lord's in May 1894 between the Marylebone Cricket Club (MCC) committee and the secretaries of the clubs involved in the official County Championship, which had begun in 1890. As a result, those clubs became first-class from 1895 along with MCC, Cambridge University, Oxford University, senior cricket touring teams (i.e., Australia and South Africa at that time) and other teams designated as such by MCC (e.g. North v South, Gentlemen v Players and occasional "elevens" which consisted of recognised first-class players). Officially, therefore, the inaugural first-class match was the opening game of the 1895 season between MCC and Nottinghamshire at Lord's on 1 and 2 May, MCC winning by 37 runs.
The term "first-class cricket" was formally defined by the then Imperial Cricket Conference (ICC) on 19 May 1947. It was made clear that the definition "will not have retrospective effect". The definition is as follows: