How are countries grouped for international football?

Answer 1

For confederation-level (continents), pots consist of nations from all over the continent with no specific grouping process. For example, Portugal can be grouped with Russia, on the other end of the continent, and with San Marino, which is at a much lower spot in the current performance ranking.

For World football (such as the World Cup), countries must qualify via a group stage in their continent in the months preceding the event. Groups contain up to 6 teams or so for Europe, and only the top 2 after a round-robin has been played will qualify. Sometimes 3rd places of all the groups compete in a playoff to add more teams to the final list of qualified nations. Once the world cup starts, there is no specific grouping policy; African teams may appear in the same pot as South American and Asian teams.