Traditional decentralized cryptocurrencies must wait for certain period of time for enough blocks to pass to ensure that a transaction is both irreversible and not an attempt to double-spend money which has already been spent elsewhere. This process is time-consuming, and may take anywhere from 15 minutes to one hour for the widely accepted number of six blocks to accumulate. Other cryptocurrencies achieve faster transaction confirmation time by centralizing authority on the network to various degrees.
Dash suffers from neither of these limitations thanks to its second-layer network of masternodes. Masternodes regularly form voting quorums to check whether or not a submitted transaction is valid. If it is valid, the masternodes “lock” the inputs for the transaction and broadcast this information to the network, effectively promising that the transaction will be included in subsequently mined blocks and not allowing any other spending of these inputs during the confirmation time period.
InstantSend technology will allow for cryptocurrencies such as Dash to compete with nearly instantaneous transaction systems such as credit cards for point-of-sale situations while not relying on a centralized authority. Widespread vendor acceptance of Dash and InstantSend could revolutionize cryptocurrency by shortening the delay in confirmation of transactions from as long as an hour (with Bitcoin) to as little as a few seconds.