Airdrop is something like a giveaway for those people in this forum that is junior member or higher rank. It is also capable of being fast in distributing coins for those who submitted to join.
It's free coins,the dev of the coin will give people according to his set preferences could be members of this forum with junior rank and higher I already participate in 5 airdrop and made a good profit from those coins,You can check the altcoin announcement for airdrop,it's the easiest way to build community,because everybody here loves free coins.