Security mechanisms are tools and processes designed to protect information and systems from unauthorized access, damage, or theft. They include methods like encryption, which scrambles data to make it unreadable without a key, and authentication, which verifies the identity of users before granting access. These mechanisms help ensure the confidentiality, integrity, and availability of data. Common security mechanisms also involve firewalls, which act as barriers between trusted and untrusted networks, and intrusion detection systems that monitor for suspicious activities. Together, these tools create a layered defense, making it more difficult for attackers to compromise systems and sensitive information.