Double-spend is a flaw with digital currencies that occurs when someone tries to use the same money for two different transactions at the same time.
In other words, how can you be sure that digital money sent to you was not simultaneously sent to someone else?
An example of this is trying to send the same bitcoin (BTC) to different wallet addresses at the same time before either of the transactions has a chance to be confirmed to the network.
A double-spend can happen by accident or it can happen deliberately, whereby someone tries to trick the network.
Since digital data like text and photos are easy to duplicate, this is a problem if you’re trying to use digital money.
Double-spending was one of the original problems that digital currencies needed to solve.
This isn’t a problem with paper money or gold, as you have to physically give up possession of either when making a payment.
Before Bitcoin, payments made digitally had to rely on a central authority, like a bank or credit card company, to keep track of transactions and account balances but, of course, his process wasn’t decentralized.
Blockchain technology solves the double spend problem.
Bitcoin is the most famous example of blockchain technology, using a proof-of-work (PoW) consensus protocol to verify transactions contained in a block, in order to add that block to the blockchain.