A key card is a small, portable card that uses a magnetic strip or embedded chip to grant access to secure areas, such as hotel rooms or office buildings. When swiped or tapped against a card reader, the key card communicates with a locking system to unlock doors or provide entry to restricted areas. Key cards are often used in place of traditional keys because they are more convenient and can be easily reprogrammed if lost or stolen. They can also be integrated with other systems, such as hotel management software or security systems, to enhance overall security and efficiency.