Organization is the act of arranging elements of varied function into a coherent, useful form.
When something is arranged in an "orderly, functional, structured whole" it is easier to understand, use and maintain. This applies to a physical environment like a work space or living space, a classroom, desk or backpack. It also applies to time, such as a daily or weekly schedule, and it applies to ideas and information, such as note-taking and writing.
Organization is very subjective. What works well for one person may not work for another. And what works for someone in one situation may not be well suited to a different situation even for the same person. When considering organizational schemes be willing to experiment, adapt, or even start over. The key is to find a systematic, harmonious pattern that supports the user.