An airdrop is often arranged by a newly formed cryptocurrency venture as a marketing promotion, the company gives away a quantity of tokens in return for social media promotion with referral bonuses, etc.
This is usually done prior to listing the coin on an exchange so there is often a month or so lag before you can sell your earnt coins but there an abundance of opportunities in this space and it all ads up.
When airdropped coins go live the value of the coin typically dives fast as everyone sells so you do need to be quick, exchanges are for ever coming up with inventive ways to mitigate this, many very dubious but it can be fun for a little while…
Another tactic which can work with airdrops is to just hold the coins and hope for a long term exponential return, it sounds like something you would hear from a scammer but most coins over $1000 in value now were airdropped for a fraction of a cent originally.
From time to time there are also airdrops done on established coins by wallet providers and exchanges where you magically receive money overnight just for having a particular wallet or exchange account.
Things to be careful of are fake airdrops, there are many scams popping up daily (mostly on Telegram), there are two instant give away’s to a fake airdrop:
1. Asking you to enter your exchange password or wallet private keys to facilitate payment.
DO NOT ENTER THEM!
2. Requesting you to send a small ETH payment to an address to register your wallet.
YOU NEVER HEAR BACK!
Then you are blocked on Telegram.
Telegram literally is like being in a wild west saloon.
Reliable Airdrop Sites
This is very similar to airdrops but will typically require a bit more work, you will need to do things like making posts to various forums, posting to facebook groups and doing numerous twitter retweets.
Rates are low but if you have spare time and nothing else to loose give them a try, I have made in excess of $100 over a few months doing this, you just have to be part of the right platform when an opportunity arises.