Clans are groups of players who join together to support each other, either materially (donating troops) or verbally (giving advice). Players can join clans once they rebuild the special Clan Castle building early on. A major component of the gameplay of Clash of Clans is clans facing off against one another. Clan leaders and co-leaders can begin wars against other clans. Each clan is then given one "preparation day" and one "war day." When a player attacks a member of the opposing clan, they receive stars based upon the amount of destruction they cause to the opponent's community. Each player is limited to two attacks per war, and the team with the most stars at the end of the war day is declared victorious, with players receiving bonus war loot if he/she use their attacks in the war and a one more war win record in the clan description.