An inventor's notebook is a valuable tool you can use to record your ideas, invention process, tests results, observations, contacts, and discussions in chronological order. When properly organized, recorded, and maintained, this important document can help you establish the claim that you are the first to conceive of an invention. Just as importantly, entries in the inventor's notebook can show proof that you have been actively pursuing the development of the invention. As an inventor, your success in obtaining a patent and challenging any claims by others may depend on how carefully and diligently you have kept the notebook.