What is a block chain?
A block chain is in the most basic terms a ledger that is used for recording transactions in a network.  Some of the most popular block chains are etheryum, and bitcoin.  The idea when you purchase cryptocurrency is you make a new transaction in the blockchain and your transaction gets a copy of every single transaction prior to yours from the general ledger.  Everything is trackable this way and every token can be accounted for.  Nothing will ever get lost.
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.
### Instruction: What is a block chain?
### Input: 
### Response: A block chain is in the most basic terms a ledger that is used for recording transactions in a network.  Some of the most popular block chains are etheryum, and bitcoin.  The idea when you purchase cryptocurrency is you make a new transaction in the blockchain and your transaction gets a copy of every single transaction prior to yours from the general ledger.  Everything is trackable this way and every token can be accounted for.  Nothing will ever get lost.