Welcome to https://zk.open-ontology.org — a Zettelkasten experiment. Zettelkasten is a tool to collect, store, retrieve and connect notes and pieces of information structured to work as a personal knowledge system. Intended to be used as the extension of one's brain, Zettelkasten is a thinking, learning, and writing tool. The multiple possible connections between notes and information make the learning process more effective and also creates a web of thoughts. Zettelkasten is a tool and study methodology developed by Niklas Luhmann.