A hard cervical collar is a medical device designed to immobilize and support the cervical spine (neck) after an injury or during recovery from surgery. It is typically made of rigid plastic or foam and features a front and back panel that encircles the neck, fastening with Velcro or straps. The collar restricts movement of the head and neck, helping to stabilize the spine and prevent further injury. It's commonly used in emergency settings for trauma patients and can also be utilized in post-operative care.