OK! Thank you for the links. Do the best teams in Germany ever play the best teams form other countries like the UK, France or Spain? I'm not talking about National teams.
Yes they do. Since the late 50's (iirc) there has been European competition in addition to domestic league and cup competitions. The European club competitions are played during the domestic season (there are some countries whose season is different because of their location and the weather, but most European seasons run from August - May (give or take).
These competitions have gone through a few different guises but essentially (and allowing for a few name changes) you had:
This was a competition for the Champions of the top division of each European League (+ the winner could defend their title, even if not that seasons domestic winner). E.g. Nottingham Forest only one the English league championship once (1978) but have won the European Cup twice (1979 and 1980) as they were allowed to defend their 79 triumph. It was when flying back from a European Cup semi-final in Belgrade in 1958 that the Manchester United air crash happened. They stopped off in Munich and while trying to take off in snowy conditions, they crashed, killing most of the glorious "Busby Babes" team. It is highly likely that Manchester United would have been the dominant force in European soccer had that not happened.
Real Madrid (Spain) were the main winners in the early years and then a number of teams had periods of dominance in the late 60's and early 70's - Ajax (Holland) Inter Milan (Italy) and Bayern Munich (Germany). Scotland's Celtic were the first British team to win the trophy (1967) and England's Manchester United won it a year later. In the late 70's and 80's, English teams dominated - Liverpool, Forest and Aston Villa.
European Cup Winners Cup
This was a competition for the winners of the main domestic cup. Tottenham Hotspur were the first English winners of this or any European trophy in 1963 (beating Atletico Madrid 5-1 in Rotterdam). A host of British clubs won this trophy.
Inter City Fairs Cup / UEFA cup
This was a competition for the best placed clubs in the domestic leagues, beginning with the runners-up. How many places were available for each country depended on the strength of the domestic league, but typically 3-4 for the bigger countries.
You could only appear in one competition and so if you won the cup and league, you played in the European Cup and the runners up in the cup played in the Cup Winners Cup. If you were one of the high finishers in the league, but won the cup, you played in the Cup Winners Cup and the club that finished in the next place down went into the ICFC/UEFA Cup.
Money talks as they say, and in more recent time (early 90's?) they got rid of the European Cup and replaced it with the Champion League. This is the premier European Competition and is where the big bucks are. You no longer have to be the winner of your league to play in it - Top countries like England, Spain etc get their top 4 teams enter. The money is so big here that getting into the top 4 in England is seen as absolutely vital to financial success.
The Cup Winners Cup and UEFA Cup no longer exist either and have been replaced with this secondary competition. ALL European football used to be played on a Wednesday night. Now, because of TV and money, the Champions League games are played on Tuesday and Wednesday nights and the Europa League is relegated to a Thursday (which does not help its popularity with managers who have a domestic game at the weekend).
The Europa League is badly maligned which is a real shame. Its a top competition and any winner has to beat top class opposition. Its a shame that so many English clubs do not take it as seriously as they should.
Anyway, I hope that potted history is helpful.
England expects that every man will do his duty. Horatio Nelson October 1805