A distributed transaction is when a single transaction affects multiple computers in different locations. This is usually done when a business needs to make sure that all of the parts of the transaction happen at the same time, or one after the other. For example, if a customer wants to make a purchase online, the money needs to be taken from the customer's bank account and sent to the store's bank account. A distributed transaction means that both of those transactions need to happen at the same time so that neither of them fails.