So before we get into decentralized applications, the first thing you need to understand is — what a blockchain is?

A blockchain is a system of storing information that makes it extremely difficult or impossible to hack, cheat or change. So, generally speaking we can trust this system and we know everything on a blockchain is true, accurate and complete information. And it’s not been hacked or modified maliciously in any way. Blockchains are used in cryptocurrencies and the way they work is, they are a digital ledger of all of the transactions that have occurred in this cryptocurrency’s history. Now this ledger is distributed to all of the different computers that are sitting on the blockchain network.