The phrase "intellectual property" describes any work that is distinct, owned, and protected by patent, trade secret, or copyright laws.
Examples of protected work:
An invention or technique that you patent (i.e.: the ARM processor in most mobile devices, designed to run fewer instructions and take up less memory).
Proprietary technology protected by trade secret laws so that an employee cannot reverse-engineer software or sell information to a competitor.
An API package protected by copyright, so that no one may use, modify, or redistribute the API without permission. (i.e.: Google copied Oracle’s JAVA API for android).
Copyright is intended for creative work, and does not protect facts, ideas, or common knowledge, such as mathematical calculations or widely-used instructions.
You may use material that is explicitly stated as:
But do not assume that any material is fair game just because it is on the internet! Look for and obey the creator's terms of use, and always give credit for someone else's work.