Let's break this word into two parts, Crypto and Currency.
The word Crypto comes from the Greek kryptós, meaning “hidden.” Crypt or Cryptography is a method of protecting/securing a piece of information through hashing, security keys, and algorithms.
A currency is just a medium of exchange through which two parties can make transactions in order to exchange goods and services.
To sum up, cryptocurrencies are digital and decentralized financial assets, a form of payment that uses complex cryptography and can be exchanged in return for goods and services.
Decentralization refers to distributing various authorities to the public in order to prevent central control. Decentralized networks strive to reduce the level of trust that participants place in one another, and deter their ability to exert authority or control over one another in ways that degrade the functionality of the network.
Blockchain is simply a decentralized public ledger that stores data in the form of blocks. Every block in the blockchain network is linked to the previous block to maintain security. In simple words, blockchain is a type of immutable, transparent, secure, and decentralized database.
These blockchain networks serve as the core infrastructure of all cryptocurrency projects, helping maintain a decentralized and secure ecosystem.
Blockchain is basically a chain of blocks that contain information. Each block contains:
Tampering with hashes of one of the blocks can result in invalidation of other following blocks. This makes blockchain one of the most secure forms of a ledger.
Check out this really cool website to understand the working on blockchain network: Blockchaindemo.io