Blockchain is a critical part of the bitcoin peer-to-peer payment system. The bitcoin system works using a blockchain ledger to record transactions. Bitcoin is a global cryptocurrency that can be used as a medium of exchange. However, while many parties have started to accept bitcoin as a currency, it is still controversial and poses risks in terms of security and stability.
The blockchain ledger helps to provide transparency for transactions. Although many bitcoin transactions are in some ways anonymous, the blockchain ledger can link individuals and companies to bitcoin purchases and ownership by allowing individual parties, called miners, to process payments and verify transactions. Rather than a central company presiding over the use of bitcoin, these blockchain originators serve central roles in the management and administration of this alternative currency system.
– definition from Techopedia