Professionals working in academia, research, industry and government document their work. This is to protect their own intellectual property and that of their employers and clients. It is also a way to record what has been done, so they, or others can build on the work. It is a way to plan what might be done next, as well as what has been done. For students this is also a good way to learn, by reviewing what they have learned, and planning what they need to learn next.