What constitutes a rivalry? Is it the passion? Is it the proximity? Is it the familiarity that breeds contempt? Is it the jealousy that one can sense when their rival is racking up the accolades? Is it the infighting between rival fans that leave many hurt, injured or even killed?
Or is it the great play in these matches that bring out the best in both sides, no matter where they are in the league table?
We at Bleacher Report are here to assure you that it's a combination of these factors as we give you the 50 greatest rivalry matches in world football from both club and country.
Sure, they may divide families, friends, cities and countries. But in the end, these derbies are part of what makes the world game the most celebrated sport on the planet.