A Go professional is a professional player of the game of Go. The minimum standard to acquire a professional diploma through one of the major go organisations is very high. The competition is tremendous, and prize incentives for champion players are very large. For example, the Honinbo Tournament has a grand prize of about $350,000.
Almost all professional players are from China, Japan, Korea, and Taiwan. This is because until recently, only China (China Qiyuan), Japan (Nihon Ki-in, Kansai Ki-in), Korea (Korea Baduk Association), and Taiwan (Taiwan Chi Yuan Culture Foundation) had professional Go organizations. In 2012, the AGA Professional System was established in the United States. In 2014, the EGF professional System was established in Europe.
Professional rankings are separate from the amateur ratings (usually 30 kyu through 7 dan). Professional rankings are 1 dan through 9 dan (sometimes written 1p through 9p). In the past, a 1 dan professional was roughly equal to a (European) 7 dan amateur. However, since the competition to become a professional has increased since the late-90s (particularly in China and Korea), it has become the case that new 1 dan professionals are much stronger than they usually were in the past.
There have also been professional Go players from the West competing in East Asian professional associations, specifically Romania, Austria, Germany, Russia, Hungary, Australia and the United States of America.
Professional dan rankings are normally awarded in Japan, China, South Korea or Taiwan, through one of the professional Go associations. The attainment of professional qualification differs in different countries:
Most professional players begin studying Go seriously when they are children, commonly reaching professional status in their mid to late teens. Some rare students achieve professional status at a much earlier age, such as Cho Chikun.
In order to qualify as a first dan professional (1p), one must have deep resources of game experience and study. In local positions, professionals are often on close ground with each other, understanding good shape, tesuji, life and death, fuseki and joseki patterns. However, in global positions they often differ in positional judgement - the global impact and interaction of josekis and differing importance of various parts of the board during the opening and middle game.
The strength differences between professional levels is usually considered to be no more than 2-3 handicap stones. Therefore, the difference between professional dan levels corresponds to about one-third to one-fourth of a handicap stone.
Each country has different rules for promotion. Ranks may, therefore, differ somewhat from country to country.
Professionals may also differ in actual strength for a number of reasons, such as promotion not keeping up with actual gains in strength, or the fact that professional ranks (unlike kyu or amateur dan) may rise, but never fall (even if the player grows weaker). This has posed some problems, esp. with regards to international rank discernment. There are currently over one hundred people who have the rank of 9p (the highest professional rank), though many of them no longer play competitively. A further distinction is that some 9p players regularly hold titles, others won some titles, some entered the title leagues, and many 9p never had the fortune to achieve any of the above.
Traditionally it has been uncommon for a low professional dan to beat some of the highest pro dans. But since the late-90s it has slowly become more common. This trend has been primarily credited to the result of increased competition to become a professional player in China and Korea. The result, that new 1 dan professionals are generally stronger than other 1 dans in the past.
In Japan, the Oteai system was reformed in 2004. The goal was to help alleviate some of the rank inflation that had crept in over the years. Today's Japanese system uses various benchmarks; for example, winning certain tournaments or a certain number of games, to be promoted by a rank. The Korean and Chinese systems have also been similarly changed in the past several years. These systems have increased the importance of international tournaments by incentivising rank promotion through international placement. Recent criticism has been given to this aspect, arguing that an individual may increase many professional ranks at once through the virtue of a single competition result (such as Piao Wenyao).
In theory, professional dans should beat all levels of amateur dans. In reality, the very top amateurs have proven very able. The conventional wisdom is that such players may achieve some of the insight of a pro, though perhaps not the detailed knowledge.
In China, Korea, and Japan, there are two distinct ranking sets, one for amateur players and one for professional players (who receive a fee for each game they play, bonuses for winning, and fees for other related activities such as teaching).
In the Japanese professional ranking system, distinction between ranks was traditionally considered to be roughly one third of a handicap stone (making the difference 3 pro dan equal to one amateur dan). The strength of new professionals (1-dan) was usually comparable to that of the highest ranked amateurs. Currently the professional ranks are assumed to be more bunched together, covering not much more than two amateur dans; so that pro 1-dans win some games against 9-dans. There are also a number of amateur players acknowledged as having pro 6-dan understanding of the game.
In South Korea, there are several amateur systems in use, with the recent introduction of official 7, 6 and 5-dan amateur ranks, each of which is somewhat stronger than the corresponding European grade. A 7-dan amateur will have won three national events, and will be effectively of lower-ranked pro standard. The older gup system does not easily match others. In practice, in Korean clubs, grades may be worked out against the resident strongest amateur.
The Taiwan Chi Yuan Culture Foundation also employs a dan system similar to that in Japan. It ranks its professional players from beginner dan (初段) up to 9 dan, being the highest. However, the amateur ranking system is established by another organization. certifies amateur player through competitions, ranking player from beginner dan (初段) to 6 dan with 7 dan being honorary.
In Germany and the Netherlands a "classes"-system (German: "Klassen") was established by Go pioneer Bruno Rüger in 1920. It comprised a further subdivision into Kyu/Dan half-grades with classes 18 and 17 = amateur 1-dan with the 17 being on the stronger side. It was replaced by the Japanese amateur ranking system in the 1970s.