Refers to information that is classified, secret, or not to be disclosed, often used in business, government, or military contexts.
You must not leak the company's confidential information to outsiders.
This document contains confidential information.
秘密 is a broader term for 'secret' or 'mystery', while 機密情報 specifically refers to classified or sensitive information, often with formal or official connotations.
Compound of 機密 (きみつ, 'secrecy' or 'classified') and 情報 (じょうほう, 'information').