When rugby union turned professional in 1995, it sparked changes in the domestic game as unions sought to create cross-border competitions in a bid to make the game more appealing and competitive.

The European Rugby Cup, or the Heineken Cup as it is more commonly known now, was launched in the summer of 1995 and has grown into one of rugby union's most prestigious and popular competitions.

The annual tournament involves 24 teams from six countries England, Scotland, France, Ireland, Italy and Wales which are split into six pools, with the top teams then qualifying for the knockout stages.

For the teams that have not qualified for the European Rugby Cup there is a second-tier competition called the European Challenge Cup.

To qualify for European cup competitions teams must qualify from their domestic leagues during the previous season.

In England the Guinness Premiership, which runs from September to May, is the top league and involves 12 teams.

The number of English clubs able to compete in the Heineken Cup depends on the success of teams in the previous season's tournament, but it is usually six.

Regional sides from Ireland, Scotland and Wales qualify for the Heineken Cup via the Celtic League - or Magners League as it is now known.

The champions are determined by their League performance, although from the 2009-10 season a play-off system will be introduced.

The other major club tournament in Britain is the Anglo-Welsh or EDF Cup, which involves 12 Guinness Premiership teams and the four Welsh regional teams initially competing in a pool format before progressing to the knockout stages.