Almost any business information can qualify, including customer lists, pricing, financial data, formulas, designs, software code and processes, if it meets two tests:
Reasonable Secrecy Measures
The owner took reasonable steps under the circumstances to keep it secret, such as confidentiality agreements, limited access and passwords.
Value from Secrecy
The information is valuable because others don't know it and can't readily obtain it through proper means.
Independent development is a proper means, and so is reverse engineering a product that was lawfully acquired, unless a contract or other law prohibits it. Our article on intellectual property basics explains how trade secrets fit with other protections.