The document discusses different queue data structures, including their operations, implementations, and uses. It covers standard FIFO queues as well as priority queues, circular queues, and double-ended queues. Standard queue operations include enqueue, dequeue, peek, isempty, and isfull. Circular queues reuse space after reaching the end to avoid overflow. Priority queues order elements by priority level rather than insertion order. C code examples are provided for array-based standard and circular queue implementations.