Bitcoin is a "peer to peer electronic cash system".
In these four words the immense essence of Bitcoin is explained.
[1] NODES of the network can be servers (users who use the services) at the same time.
All this leads to a decentralized system but that does not yet bear the name BLOCKCHAIN (which we will explain in the next article)
ELECTRONIC CASH SYSTEM: Internet has always been a "place" where you can exchange anything but before the advent of Bitcoin still lacked something: the exchange of VALUE.
With the advent of Bitcoin we finally have the creation and exchange of value, an element that is missing from the Internet.
[1] NODE is any device (computer and smartphone for example) that is able to interact with other devices.