Information does two things. It moves between points, and it gets acted on at the points. These are not the same activity. Moving a message from New York to London is different from understanding it once it arrives. Transmitting a chest X-ray to a radiologist is different from the radiologist reading it. Delivering a notification to a developer's screen is different from the developer deciding what to do about it. Movement and action. Transit and processing. Channel and endpoint. In 1948, Claude Shannon formalized the first half. His mathematical theory of communication gave exact answers to the questions of movement: how many bits can a channel carry, how should a message be encoded for efficient transmission, how can noise be overcome. His theory is among the most successful in the history of science, and its unit — the bit, one binary distinction — became the foundation of the information age. Shannon explicitly excluded the second half. What happens at the endpoints — how a source decides what to transmit, how a destination makes sense of what it receives — he declared out of scope. The source produces symbols; the destination receives them. What either does with those symbols, Shannon left to others. This paper presents the second half and shows how both halves compose into a single complete theory. Shannon gave us the bit — the unit of information in transit. The framework presented here gives us the **op** — the unit of information under action. Together, bits and ops cover everything information does.
Geoffrey Howland (2026) studied this question.