The principal of information security is to protect the confidentiality, integrity and availability of information from harm. These principals together are known as the CIA Triad.
The CIA triad consist of three objectives: confidentiality, integrity and availability.
Confidentiality is assurance of data privacy. Only the intended and authorized recipients may read the data. Disclosure to unauthorized entities, for example using unauthorized network sniffing is a confidentiality violation.
Countermeasure: Cryptography is the art and science of storing and transmitting confidential data.
Integrity is assurance of data non-alteration. Data integrity is having assurance that the information has not been altered in transmission, from origin to reception.
Countermeasures: Digital Signatures and hash algorithms are mechanisms used to provide data integrity.
Availability is assurance in the timely and reliable access to data services for authorized users. It ensures that information or resources are available when required.
Countermeasures: High availability protocols, fully redundant network architectures and system hardware without any single points of failure ensure system reliability and robustness.