How are the teams selected?
The Champions League is a European soccer competition, this makes almost all of the top European soccer leagues eligible to participate in the competition. Although this is a European soccer competition there are still a few countries that are unable to participate in it, like Ireland, Iceland, Belarus, and Albania.
Each country has its soccer league in which teams compete to win their national competition. Teams also compete for a spot to play in the Champions League. National leagues like the Premier League (England), La Liga (Spain), Bundesliga (Germany), and Serie A (Italy) all teams that are in the top 4 in their respective leagues are automatically placed in the group stage. In other countries, only the league winner or top 2 of the league get a spot in the group stage.