What is the Kolpak rule?
Citizens of EU countries are allowed to work in any other EU country. But the Kolpak rule means that citizens of countries that are part of European Union Association Agreements, which are free trade treaties between the EU and other countries, also have the same right.

Why is it called that?
The rule was made when Maros Kolpak, a Slovak handball player, appealed to the European Court of Justice that he should not be considered a non-EU player in the German handball league as he was a resident of Germany and a citizen of a country that had an Association Agreement with the EU. Kolpak had lost his contract with his German club as they already had two non-EU players. The court ruled in his favour.

How does it impact cricket?
Players from countries with such deals with the EU can play cricket in any EU country without being considered an overseas player. This means they can sign contracts with English county sides without having to be fielded as overseas players.

So how do South Africans qualify?
South Africa is part of a deal called the Cotonou Agreement with the EU. Zimbabwe and several Caribbean nations are also signatories, so their players are eligible for Kolpak deals too.

Can any South African player sign a Kolpak deal?
No. In 2009, the British Home Office ruled that to sign a Kolpak deal, a player must either have a valid work permit for four years in the UK or have earned a specified number of caps in international cricket.

Can a Kolpak player play for his own country while playing for an English county?
No. A player must give up his right to play for his country during the length of his deal with a county.

Can a player play domestic cricket in both England and his home country when on a Kolpak deal?
Yes, but he can only play in the English off season. His English county has to be his priority.

Can a Kolpak player come back to playing for his country of birth?
Yes, once his contract with the English county expires or is terminated. Jacques Rudolph signed a Kolpak deal with Yorkshire in 2007 after being dropped from the South African team in 2006. He was released from it in 2010 and played again for South Africa in 2011.

Can a Kolpak player play for England?
Kolpak players over 18 do not qualify to play for England till they have played seven years for a county and have gained citizenship. This was increased from four years in 2012.

So how do so many players born in other countries play for England?
Players such as Kevin Pietersen and Jonathan Trott played for England not through Kolpak deals, but because one of their parents or grandparents was English.

How will Brexit affect Kolpak?
Once Britain leaves the European Union, Kolpak contracts will most likely not be possible. That is why there is a rush now from counties and Kolpak-eligible players to sign deals before Brexit takes effect.

What's in it for the players?
More money. South African domestic cricket pays significantly less than English county cricket. And with the South African rand weakening, the gap is widening.

But why would a member of the South Africa international team give up Test cricket?
South African cricket has a quota system. In September last year, Cricket South Africa announced that a maximum of five white players can be picked in the eleven, on average. This means some white players, such as Kyle Abbott and Rilee Rossouw, may not get as many chances to play for South Africa and are hence choosing to move to England.

What's in it for the counties?
They get better players without having to field them as foreign players. Each county is only allowed to field one overseas player (or two in the NatWest Blast). So, basically, it is like Royal Challengers Bangalore being able to sign Chris Gayle and AB de Villiers and play them without counting them as foreign players.

What are the negatives?
For countries such as South Africa, the drawback is that they lose players from their national side and their domestic competitions. For England, fewer English-born or England-qualified players get the chance to play county cricket.