And then there's copyright
It's not just plagiarism you have to be concerned about. As a college student, you'll be expected to use copyrighted information appropriately. If you use a work without receiving permission from the creator, you're committing a major offense: you're violating copyright laws.
Copyright protects big corporations who have unique products, such as Disney's Mickey Mouse. Copyright law also protects individual creators like professors and students. Every time we produce something unique, our work is automatically protected by copyright law, with or without a symbol or a copyright statement.