Applications
Applications that require low latency (such as telephone conversations) cannot use Automatic Repeat reQuest (ARQ); they must use Forward Error Correction (FEC). By the time an ARQ system discovers an error and re-transmits it, the re-sent data will arrive too late to be any good.
Applications where the transmitter immediately forgets the information as soon as it is sent (such as most television cameras) cannot use ARQ; they must use FEC because when an error occurs, the original data is no longer available. (This is also why FEC is used in data storage systems such as RAID and distributed data store).
Applications that use ARQ must have a return channel. Applications that have no return channel cannot use ARQ.
Applications that require extremely low error rates (such as digital money transfers) must use ARQ.
Read more about this topic: Error Detection And Correction