A Zettelkasten is a personal tool for thinking and writing. It has hypertextual features to make a web of thought possible. The difference to other systems is that you create a web of thoughts instead of notes of arbitrary size and form, and emphasize connection, not a collection.
- Sascha Fast

The hypertextual features of a zettelkasten (especially a digital one) might put you in mind of a Wikipedia page, but that's not how it works. Instead of long notes with multiple sections that cover most of the topic, a zettelkasten is a collection of shorter notes, with each not containing a single fact or idea, that are linked to other similar facts or ideas.

The atomicity of the notes in a zettelkasten allows them to be reused in in several trains of thought. This gives rise to a network of thought and allows for connections between seemingly disparate ideas and subjects. It is this ability to connect ideas that allows the zettelkasten to aid the user in generating novel thoughts and arguments.

Source: zettelkasten.de

See: 5.3a main notes in a zettelkasten should be atomic for more on the atomicity of notes in a zettelkasten

See: interoperable for more on self contained components

See: seredipity machine for more on generating novel thoughts and ideas