Writing is any mark-making intended to communicate something, regardless of legibility.

The substrate is the stage or context on which something occurs. The substrate is not agnostic; its material conditions shape what can be made visible and the duration of that visibility.

The marking material is the substance or medium that enables a mark to appear on a substrate, regardless of how long the mark remains visible.

The marking tool is the object used to apply the marking material to the substrate.

The writer is the entity—across species and beyond the living/dead binary—that uses a marking tool and marking material to create an intentional mark on a substrate.

The interaction among the writer, marking tool, marking material, and substrate produces a mark.

The environment within which this interaction occurs is called the writing ecology.