Confidentiality seeks to prevent the unauthorized disclosure of the information. Data is accessible to users who have formal access approvals, security clearances and on need to know basis. In nutshell, Confidentiality prevents read access to data and you need to have permissions or authority to do so.
Integrity seeks to prevent unauthorized modification of the data. Integrity prevents write access to the data. Integrity ensures quality and consistency of the data.
Availability, ensures that the information is available when needed. Availability demands both hardware and software to be available without any interruption.