What is Blockchain technology in simple terms?

In the simplest terms, a blockchain is a computer file for storing data and that data  which is contained within the blockchain is distributed (duplicated) across many computers (decentralised).

In more detailed and technical terms, the blockchain relies on peer-to-peer network technology,whereby the entire system is composed of peers (or nodes). Each peer in the network approves and record each transaction that takes place in the network.What this means is,that whenever a new transaction is added to the network, it is verified and added to each peer's ledger. This decentralized way of recording transactions in a ledger is called Distributed Ledger Technology(DLT).

Blockchain is a type of DLT. Each transaction stored in the blockchain is called a block. Each block is chained to the previous block using a cryptographic hash.So, if someone wants to tamper with a certain black ,they have to tamper with all the previous blocks in the chain, which is impossible/ extremely difficult since all peers have the same ledger, and any change is noticeable.This creats an immutable record of blocks, that does not require on external authority.

Hence, in the simplest terms,a blockchain is a chain of blocks. it is a process or technology of recording information as blocks that makes it impossible to change, hack,or cheat.