Day-to-day, we learn new things, it could be from a blog, video, book, people etc.. The new information may be helpful to develop a skill, solve problems, become better. However, our brains are not good at remembering and recalling information when we need it. This is because of memory declines over time (Forgetting Curve).
When need a system to store information. Easiest and simplest form of storing is by noting the information in a notebook. The very process of writing down the newly acquired information, especially when we write it in our own words (rather than copying from source), makes us to understand it better and increases the strength of that memory in the brain.
Notes serves as a long term storage medium helping us to revise in the future and eventually to remember easily.
After a lecture, meeting, reading a material, or after a significant experience, spend a minute to understand the idea and note down the most important notes.