Basics of the Blockchain and Cryptocurrencies - Part I

Introduction
In this series of posts I will explain the basics behind the functioning of a blockchain and its use for cryptocurrencies. Since it is a basic explanation I will refrain from using technical terms or I will explain the terms if used. Further down the road I will post some advanced explanations on specific blockchains and the security of them.

Chapter I

History
The concept of a secured chain of blocks was introduced in 1991 by Stuart Haber and W. Scott Stornetta. But its first use was introduced by an anonymous entity (It is unknown if it was just one person or a group of them) with the alias "Satoshi Nakamoto". His/Her/Their objective was to create an autonomous, easy-to-access , self-working and free of centralized management economy system, with low fees, fast transaction times and high security level.

What is a blockchain?
A blockchain is basically a registry (Database). So, what makes it so special?
This kind of database is an append-only database, which makes it so that information can be stored, but once it is there it is impossible to take it out or change it. It is distributed, this means that it is stored in a group of computers (nodes), this makes it very difficult to attack, because if you manage to successfully attack one of the nodes and change something in the database it will be useless unless you can change all the nodes at the same time. This means that the more nodes there are, the more difficult it is to make a successful attack on the network.
The blockchain is, as the name says it, made of a chain of blocks. The blocks are organized from oldest to newest. Each block contains a reference to the previous block, a timestamp and whatever information the given blockchain is supposed to store. Yes, a blockchain can be used for purposes other than cryptocurrencies.

Again, this is a basic explanation and each block is more complex than explained, but I can explain more when I make an advanced series.

And this is the first chapter of my series on the basics of the blockchain and cryptocurrencies!
If there is any typo or error feel free to point it out. And ask any question you have.