Some eResources and Companion Materials are specially customized for a particular school, course, or instructor. In order to make sure that you get the right version, you will be asked to enter an Instructor Code. This is a URL or other ID that you will get from your Instructor or your class syllabus.
The Product Detail page of the eTextbook or eResource will tell you that “To use this product you will need course-specific information from your instructor.” The little green key symbol also indicates that an Instructor Code will be needed.
If the eResource or Companion Material requires an Access Code, you will need the Instructor Code and Access Code at the same time, so make sure you have the Instructor Code (if required) before you reveal the Access Code.