How does an operating system provide security?

The operating system provides various techniques which assures the integrity and confidentiality of user's data. Following are the security measures which are used to protect the user's data from threats and intrusion:

1. Protection against unauthorized access through login and password.
2. Protection against intrusion by keeping the firewall active.
3. Protecting against malicious access to system memory.
4. Displaying messages related to system vulnerabilities.