The word confidential means something done or said or communicated in secret. Confidential information is information that should be shared only by those that need to know and could be harmful if known to enemies, for example things that pertain to national security and secret military operation that depends on army personnel to maintain confidentiality.
During the time of war it is very important to keep secrecy and confidentiality. For example, the American secret service, the CIA (Central Intelligence Agency) runs operations in many countries as does RAW, the Indian intelligence agency. Their success depends on confidentiality. Confidentiality is essential to run a successful business, so that your ideas and information cannot be stolen by business rivals. Even inventor's needs to keep their idea a secret before getting a patent, so as to avoid other people selling their ideas and inventions and having it patented in their name. During confession in a church the priest is expected to keep the things told to him a secret.
During the time of war it is very important to keep secrecy and confidentiality. For example, the American secret service, the CIA (Central Intelligence Agency) runs operations in many countries as does RAW, the Indian intelligence agency. Their success depends on confidentiality. Confidentiality is essential to run a successful business, so that your ideas and information cannot be stolen by business rivals. Even inventor's needs to keep their idea a secret before getting a patent, so as to avoid other people selling their ideas and inventions and having it patented in their name. During confession in a church the priest is expected to keep the things told to him a secret.