What is Double Spending?

It is the problem of spending the same title (coin) more than once.

Bitcoin was the first to solve the problem using the shared ledger (blockchain), a peer-to-peer network and a consensus mechanism (Proof of work) connected to a reward.

A digital problem

With a digital currency (a file, a set of strings) I can copy and create many identical copies of a file

In the field of digitization, the concept of source originality for the file is lost, because the two files are identical.

The solution before Bitcoin was to use a central unit, a certification authority that guaranteed that I did not spend the same coin twice.

The Bitcoin solution

Problem solved through a peer-to-peer network

The solution is based on the idea that if the majority of nodes behaves correctly, the network is secure (51% attack) because nobody can attack the system.

Moreover, dishonest behaviour is economically damaging compared to blockchain. Therefore, for a node, it is more profitable to behave honestly to get a reward in bitcoin or its fractions.  

The original idea of Nakamoto’s article is that introducing a currency reward is the best way to ensure that all nodes behave properly.

Do you want to start digitizing your certificates?