Blockchain or simply chain of blocks. It consist of multiple blocks, and a block is added to that chain when that block store a new data... It's hard to discuss everything here so you can just read this link I've searched. And I guess it will help you learn and understand some basics about blockchain and how it works. https://www.investopedia.com/terms/b/blockchain.asp
The blockchain works as a record of transaction that represent a financial ledger entries in the structure. The majority of nodes are approved by each transaction that was written in a block. These all blocks refer to the earlier block by joining together just like a spreadsheet that is called as Blockchain.
Blockchain is a set of multiple data that exists in multiple computers. It consistently grows as new data or records are added and it has a timestamp to show when data is recorded. Blockchain actually can be applied anywhere where peole wants to avoid middleman and wants decentralisation. It can be used for property, keeping medical records, and a lot more.
Different blockchain works by utilizing different hashing algorithms that makes it possible to make secure transactions because based from the concept of hashes, it could not be turn back to its original state. Meaning to say if a certain line of code is hashed, it will fully hide the code and that's the basic principle why transactions are secured in blockchain.
One other thing why blockchain couldn't be easily hacked is because all hashes are connected to their predecessor, so imagine if we change one block, the entire continuum of blocks will be totally different.
Blockchain technology is containing all the informations of each of every transactions entering everyday which this transactions are converted to hash value to make it invulnerable to public. Thus, every transactions by a nodes it will consider as a block that will added to the previous blocks.
The Blockchain serves us a public database that consists of series of block that is composed of cryptography and hashing codes that protects the private data. This is applicable in cryptocurrencies and other fields.