Final answer:
A dead letter queue is a queue that other (source) queues can target to send messages that could not be successfully processed.
Step-by-step explanation:
A dead letter queue is a queue that other (source) queues can target to send messages that for some reason could not be successfully processed.
For example, let's say there is a messaging system where messages are sent from one queue to another. If a message fails to be processed successfully, it can be moved to a dead letter queue for further analysis.
This concept is commonly used in message-oriented middleware systems to handle failed or undeliverable messages.