Three time stamps worth considering with each noted piece of knowledge: When was the note made? I watched a recorded lecture on exoplanets two months ago. I took notes then. That was the time stamp. When was the source of the notes made? The lecture was recorded in 2015. All information on exoplanets might not be up to date at the time of writing notes two months ago, but even if I watched the lecture in 2015 this would still be true today. What time is the source of the knowledge referencing? I learned what some team discovered in 2011. To the best of professors knowledge this was still true, but in general case the source of the knowledge itself might be out of date or less informed. #pkm #TakingNotes