A way of distributing free cryptocurrency or tokens to users. This can occur by simply holding an account with a partnered exchange or holding a compatible cryptocurrency, such as ETH or Bitcoin, in a specified 3rd party wallet or can even take place in completely public events. Sometimes both apply i.e. an exchange may require you to hold a certain amount of one coin, before you can receive another. It is seen by some as a PR exercise, and by others as a viable option / alternative to ICOs for fairly distributing an asset. Once received, these assets then become transferable and tradeable on the open market. Airdrops can also occur in the form of a hard fork, where the original version of the cryptocurrency is required, and a blockchain ‘snapshot’ of ownership is taken before the owner of the original cryptocurrency receives the new, forked version of cryptocurrency.