Velocity checking is the functionality to decline or approve a transaction based on real time rules applied to transactions, these might include things like:
- checking how many times a credit card has been used in last x hours
- checking how much was spent on the same credit card in the last x hours
- checking to see if the credit card appears on some white or black list
- combinations and variations of amount spent, number of times encountered, and inclusion/exclusion from lists.
Rules are applied real time (before the transaction is submitted to the bank), minimizing the risk of fraudulent transactions.