Confidentiality refers to the protection of information from disclosure to unauthorized entities (organizations, people, machines, processes). No one may read the data except for the specific entity (or entities) intended. Information includes data contents, size, existence, communication characteristics, etc.
Confidentiality is a requirement
Furthermore, given the sophistication and power of determined adversaries today, cryptographic techniques for providing confidentiality must be employed for all sensitive data. As with data integrity, this requires a common understanding between entities of appropriate algorithms and keys.