An airdrop is the giveaway of coins to those participants of the project who have performed certain actions specified by the organizers or meet certain eligibility criteria. There are two main types of cryptocurrency airdrops—automatic and incentivized.
An automatic airdrop refers to the situation when holders of a certain cryptocurrency receive new coins created as a result of a hard fork of the network. The main condition for getting such an airdrop is storing the pre-existing coin in the wallet or on the exchange that would support the fork.
An incentivized airdrop means that one receives coins for performing some tasks to promote the project, e.g., advertising, posting promotional content on the news resources, or leaving comments on the forums.