HIPAA has established boundaries for use and disclosure of __________ (PHI).

The correct answer is the phrase "Protected health information," commonly abbreviated as PHI. HIPAA, which stands for the Health Insurance Portability and Accountability Act, was created to safeguard sensitive patient information from being disclosed without the patient's consent or knowledge.

Protected health information encompasses any individually identifiable health information held or transmitted by a covered entity or its business associate, in any form or media, whether electronic, paper, or oral. This includes not only the specific health data pertaining to a patient but also personal identifiers such as names, addresses, and social security numbers.

Other terms listed in the choices, such as "private health information," "patient health information," and "portable health information," do not have the same legal implications or recognition under HIPAA as "protected health information." These terms may be used informally in healthcare settings but lack the specific definitions and protections established by HIPAA. Therefore, understanding that PHI refers to protected health information is essential for complying with legal standards related to patient privacy.