There’s this idea of spaced repetition, roughly the concept is that you get reminded of a certain piece of information after a certain period of time, and often a number of times to help you retain information longer term.
This can be done manual through notes and cards. There are also a bunch of apps that have these built in.
Another way to achieve this similar effect is to use forums as a place to take notes. And then to have someone come weeks, months or years later to interact on said post. Typically this would be by liking it or adding a comment.
This happens to me frequently and it encourages me to re-read past posts and remind me about concepts that are still worth thinking, sharing and writing about.