Confidentiality means only authorized people can access information. Fail here and sensitive data leaks to attackers or the public.
You protect confidentiality through:
Encryption. Data is unreadable without the correct key. TLS protects transit. AES protects storage.
Access controls. Only authenticated users with proper authorization can view resources.
Network segmentation. Sensitive systems are isolated from general traffic.
A breach can mean stolen customer records, leaked trade secrets, or regulatory fines.