Very important page with a lot of details about copyright and fair use. For example “Fair use is a right that you employ simply by accessing material, copying it and incorporating it into your project within an appropriate context. You do not need to get anyone’s permission to do that, and you do not even need to let them know that you did it.” (my emphasis) Btw, you will want to keep in mind that the concept of “fair use” used here applies to US copyright. Depending on where you live, your mileage might vary.