What is a Blockchain?
All cryptocurrencies use distributed ledger technology (DLT) to remove third parties from their systems. DLTs are shared databases where transaction information is recorded. The DLT that most cryptocurrencies use is called blockchain technology. The first blockchain was designed by Satoshi Nakamoto for Bitcoin.
A blockchain is a database of every transaction that has ever happened using a particular cryptocurrency. Groups of information called blocks are added to the database one by one and form a very long list. So, a blockchain is a linear chain of blocks! Once information is added to the blockchain, it can’t be deleted or changed. It stays on the blockchain forever and everyone can see it.
The whole database is stored on a network of thousands of computers called nodes. New information can only be added to the blockchain if more than half of the nodes agree that it is valid and correct. This is called consensus. The idea of consensus is one of the big differences between cryptocurrency and normal banking.
At a normal bank, transaction data is stored inside the bank. Bank staff makes sure that no invalid transactions are made. This is called verification. Let’s use an example;
George owes 10 USD to both Michael and Jackson. Unfortunately, George only has 10 USD in his account. He decides to try to send 10 USD to Michael and 10 USD to Jackson at the same time. The bank’s staff notice that George is trying to send money that he doesn’t have. They stop the transaction from happening. The bank stopped George from double spending which is a kind of fraud. Banks spend millions of dollars to stop double spending from happening. What is cryptocurrency doing about double spending and how do cryptocurrencies verify transactions? Remember, they don’t have stuff as the bank does!
Next video: Blockchain Nodes.
Video by Dan Slama
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