What is Blockchain?

Blockchain is a popular word in the depths of the Internet recently. In this article, I will try to expose what the famous Blockchain is and what it can be useful for.

This article was translated from Polish using Google Translate. The original post can be found on my blog at https://blog.budzynskimaciej.pl.

Data structures

At the beginning, it is necessary to explain what data structures are to be able to understand what blockchain is. Data structures, in general, are a way of organizing, managing, and storing data in a computer's memory. More specifically, a data structure is a collection of data values, the relationships between them, and the functions or operations that can be applied to the data. Different data structures serve different purposes, such as relational databases that use B-tree indexes to retrieve data, and some compiler implementations use hash tables to look up identifiers. The data structures include:

• Record, also known as a structure or a tuple (e.g. a point with coordinates X, Y)
• Tables
• List (one or two way)
• Object
• Tree
• Hash table
• Graph

and many, many more of the different variations of the above data structures.

Blockchain

Blockchain is a data structure. Specifically, it is a kind of one-way list containing strongly interconnected blocks using cryptography. Each block contains the previous block hash, timestamp, and transaction data. The exception is the so-called Genesis Block. It is the first block to form a chain of links with other blocks. The assumption of the blockchain is resistance to data modification and easy verification if the data has not been counterfeited. Modification of any block results in the generation of completely different hashes for subsequent blocks, which allows you to easily verify that the data has not been counterfeited.

What is it for and who is it for?

Currently, the use of blockchain is primarily the support of various transactions, such as:

• Stocks
• Currencies
• Trade

The main application of this data structure can be seen in cryptocurrencies such as Bitcoin. In the next articles I will try to implement an example blockchain.