A phenomenon that is characterized by a malfunction in a blockchain network such that a particular cryptocurrency can be spent more than once.
Double spending occurs when users can spend a cryptocurrency more than once due to errors in the transaction record on the blockchain. This is an occasional problem that happens when there is a breach on a blockchain network, often in the form of a malicious attack. This attack (known as a 51% attack) opens up the accounting ledger to errors. In this way, a user can spend their cryptos, modify the block with records of the transaction, and reclaim the spent coins to use at a later time.
Double spending is one of the gaps that can arise from using blockchain technology. However, following recent innovations in crypto space, the odds of double spending occurring is very low.