Mastering Blockchain Programming with Solidity

Blockchain solves the double-spending problem

As we know, we can share documents and pictures over the internet with someone. When we share those documents or pictures with another person, we actually share a copy of the file. Once that copy is sent to another person, you and the other person have the same copy of that document.

However, things such as money, bonds, and shares must not be shared as copies, like we do for documents/pictures when we need to transfer them over the internet. If you try to send money P2P, without using any intermediaries, then both parties end up having the same copies of the money. This is called the double-spending problem.

For example, if Alice gives a $10 bill to Bob, then Alice must not hold a copy of the ...