In the Board Game, Settlers of Catan, a die roll of what number causes the Robber to attack?

In the board game Settlers of Catan, a die roll of 7 causes the robber to attack. This number is significant because it represents an imbalance in resource distribution. When a player rolls a 7, they have the power to move the robber to a different hex on the board, blocking resource production for that hex and potentially stealing a card from a neighboring player. This mechanic adds an element of strategy and competition to the game, as players aim to control and distribute resources effectively while also protecting their own settlements and cities.