Blockchain is an immutable and distributed ledger of transactions. It is called a blockchain because it is made of a growing list of records or blocks. Each block contains a set of transactions linked to the previous block through a cryptographic hash.
A cryptographic hash function (CHF) is a mathematical algorithm
data of arbitrary size (often called the "message") to a bit array
of a fixed size (the "hash value
," "hash," or "message digest"). It is a one-way function
, that is, a function for which it is practically infeasible to invert or reverse the computation - Wikipedia
The peer-to-peer network that maintains the blockchain and provides a platform for the execution of smart contracts is called a Blockchain Network.
Bitcoin was the first blockchain network launched in 2009 by a pseudonymous person or group of persons called Satoshi Nakamoto. It was built to introduce a decentralized currency - Bitcoin, which could be transferred without any centralized intermediary.
Both the blockchain network & the digital money on the Bitcoin network is called Bitcoin
Vitalik Buterin published the whitepaper of Ethereum in 2013, defining a general-purpose blockchain network that would enable the development of other decentralized applications in addition to a digital money.
Decentralized Finance is a collective of decentralized applications that focuses on financial services.
The Ethereum blockchain network is called Ethereum, while the digital money on the network is called Ether (ETH).
Today, hundreds if not thousands of blockchain networks exist.