The Visegrad Group

The Visegrad Group , also called the Visegrad Four, or V4 is an alliance of four Central European states – Czech Republic, Hungary, Poland and Slovakia – for the purposes of furthering their European integration, as well as for advancing military, economic and energy cooperation with one another.The group used to be occasionally referred to as the Visegrád Triangle, due to the fact that it was originally an alliance of three states – the term has not been valid since 1993, but does continue to appear sometimes.
The Group traces its origins to the summit meeting of leaders from Czechoslovakia, Hungary and Poland held in the Hungarian castle town of Visegrád on 15 February 1991 (not to be confused with Vyšehrad, a castle in Prague, or with the town of Višegrad in Bosnia and Herzegovina). After the dissolution of Czechoslovakia in 1993, the Czech Republic and Slovakia became independent members of the group, thus increasing the total number of members to four. All four members of the Visegrád Group joined the European Union on 1 May 2004.
The Group's name in the languages of the four countries is Visegrádská čtyřka or Visegrádská skupina (Czech); Visegrádi Együttműködés or Visegrádi négyek (Hungarian); Grupa Wyszehradzka (Polish); and Vyšehradská skupina or Vyšehradská štvorka (Slovak).