Writing a diary is very important thing, everyone must practice to start writing diary. Like in computer systems we have three main components. First one is processor. Second one is RAM and third is our storage. If we look at these three components wisely, then we will find that CPU and RAM keep the content only when they are running and storage keep the content for long time. Despite all these RAM and CPU are the most costly part of computer as compared to the storage which is storing all our data and keeping it persistent for a very long time. In the same way, we should not use our brain to store the content. Rather, our brain should be only used for processing the content. So writing a diary means storing your content into a physical form and keeping your brain free for processing. It will allow your brain to work on multiple task without getting distracted because the data is stored in physical form in your diary. You can look up at the data anytime. It is always available for you. But if you will keep your data in your brain then when your brain is full like your RAM is full then it will be removed from your brain, once you sleep or once you switch from one task to another task so everyone should write a diary and keep tracking your activities, to do list and your notes in physical form.