Blockchain Technology - II (Data Storage)

DATA STORAGE: What is a blockchain?

A blockchain is just a file.  A blockchain by itself is just a data structure.  That is, how data is logically put together and stored. Other data structures are databases (rows, columns, tables), text files, comma separated values (csv), images, lists, and so on.  You can think of a blockchain competing most closely with a database.

Blocks in a chain = pages in a book
For analogy, a book is a chain of pages. Each page in a book contains:

• the text: for example the story
• information about itself: at the top of the page there is usually the title of the book and sometimes the chapter number or title; at the bottom is usually the page number which tells you where you are in the book. This ‘data about data’ is called meta-data.

Similarly in a blockchain block, each block has:

• the contents of the block, for example in bitcoin is it the bitcoin transactions, and the miner incentive reward (currently 25 BTC).
• a ‘header’ which contains the data about the block.  In bitcoin, the header includes some technical information about the block, a reference to the previous block, and a fingerprint (hash) of the data contained in this block, among other things. This hash is important for ordering.