32 teams qualify for the Champions League every season. The 32 sides are then split into four pots. The stronger teams are supposed to be in Pot 1, the weaker teams in Pot 4, so that each Champions League will be balanced.
Pot 1 consists of the competition winners from last season, plus the holders of the Europa League – that's Real Madrid and Eintracht Frankfurt, respectively. The other slots are filled by the domestic champions of the top leagues in Europe, according to UEFA coefficient. In the event that there is overlap between competition winners and domestic champions, the number of league champions in Pot 1 may rise or fall. This season, there are six.
The other 24 teams are ordered purely by coefficient and placed from Pot 2 to Pot 4.