In the context of Australian privacy law, personal information is any information or opinion about:
Examples include an individual’s name, signature, address, telephone number, date of birth, medical records, bank account details, employment details and commentary or opinion about a person.
If information is de-identified it will no longer count as personal information. Note: it is hard to properly de-identify information, because it is easy to cross-reference information online and find out individuals' identities.
For more information, see the APP Guidelines.