Airdrop is the practice of distributing tokens, usually for free, to a defined set of wallet addresses — typically users who interacted with a protocol before its token launch, or holders of a specific NFT, or sometimes simply random addresses meeting eligibility criteria. Two of the best known are Uniswap (September 2020, 400 $UNI to each of ~250,000 addresses, worth roughly $1,200 at launch and around $18,000 at the May 2021 peak near $45) and Arbitrum (March 2023, $ARB to ~625,000 addresses).
Why airdrops happen
Three reasons protocols airdrop:
Distribute tokens broadly to bootstrap decentralization. Uniswap's airdrop is the textbook case: tokens went straight to past users of the protocol, with no public presale.
Reward "loyal" users. Most modern airdrops target users with on-chain history at the protocol — depositors, traders, voters, NFT holders. The economic theory: align tokenholders with users.
Market the protocol. Airdrops generate Twitter buzz, attract speculative users, and create a press cycle. The cynical version of every airdrop is "free marketing budget paid in tokens." The user has to evaluate whether the marketing benefits the protocol's long-term value.
The IRS treatment for US holders
Airdrops are taxable income at fair market value on the date of receipt, per IRS Rev. Rul. 2019-24. The tokens become a cost-basis asset; any subsequent sale or swap is a separate capital gains/losses event.
This is the surprise to plan for. Suppose you claim a $5,000 airdrop on December 28, 2024 (token price $10 each), hold through a crash, and finally sell at $0.50 in March 2025. The result is tax on $5,000 of income plus a $4,750 short-term capital loss. Net tax outcome can be substantially negative; the loss helps but does not fully offset the income.
For valuable airdrops, plan the claim timing if possible. Some protocols allow claims over an extended window — claiming at a lower price point can reduce the income tax burden.
Airdrop phishing
The airdrop attack to watch for first is the fake claim page. The attacker sets up a clone of the legitimate claim site, gets a high search-engine ranking via paid ads, and prompts a "claim" action that is actually a setApprovalForAll signature. The user signs, expecting tokens; the attacker drains the wallet.
Defense: visit the official protocol website only from a bookmark or the verified Twitter link. Never from a Google ad result, Telegram DM, or Discord announcement message. Verify the official URL on multiple independent sources before connecting your wallet.
Airdrop farming
The practice of strategically interacting with protocols that have not yet launched tokens, in the hope of qualifying for the eventual airdrop. Before spending on it, check whether the project has already launched its token; once that has happened, the airdrop you are farming for may never come.
Farming consumes capital in transaction fees and time, and protocols can exclude addresses they judge to be Sybil farms. Approach it as a hobby with capped downside, not an investment strategy.
Further reading: Phishing, setApprovalForAll.