What is Personal Knowledge Management?
Personal knowledge management, or PKM, is the individual practice of capturing, organizing, connecting, and reusing the information you encounter, so that reading and experience accumulate into usable knowledge instead of evaporating. It spans tools like note apps and highlighters and methods like Zettelkasten, second brains, and Harold Jarche's seek, sense, share loop.
PKM treats knowledge work as a personal supply chain. Information comes in from reading, conversations, and work; it is filtered, annotated, and stored; it is connected to what you already have; and it goes out again as decisions, writing, and shared ideas. Jarche's seek, sense, share framework describes the loop at the level of habits, while systems like the Zettelkasten and Tiago Forte's second brain describe concrete architectures for the middle steps.
The learning-science reason PKM matters is that human memory is a poor archive. The forgetting curve guarantees that unaided reading decays quickly, so a trustworthy external store, searchable notes, highlights, and links, is what allows spaced revisiting and recombination of ideas over years.
The recurring failure mode is capture without return: saving everything and revisiting nothing. Effective systems are judged by retrieval, whether the right note resurfaces when you need it, which is why practices such as regular reviews, linking on entry, and writing summaries in your own words matter more than the choice of app.