Popularity is a measurement of the amount of fans a team has. It's calculated by taking the amount of casual fans of a team, adding 4 times the amount of normal fans and 25 times the amount of fanclub members.
The higher the popularity of a team, the more people are likely to come to their home matches.
You can see the popularity of a team on the overview page of that team. You can also see the popularity of the teams in your league when you click the "clubs" tab in your league overview. If you click the "popularity" header in the table, the teams in your league will be sorted by popularity.
