A Deque (pronounced "deck") is a data structure that allows the insertion and removal of elements from both ends, making it a double-ended queue. This flexibility enables efficient operations for adding or removing items at either the front or the back, which can be useful in various applications like scheduling and buffering. In programming, deques are often implemented using arrays or linked lists. They are part of many standard libraries, such as the C++ Standard Template Library and Python's collections module. Deques can be particularly advantageous when you need to maintain a list of items that require frequent updates from both ends.