"We value working software over comprehensive documentation", "the value is in the conversation", "the code is the documentation", and "the tests are the documentation" are all statements you'll hear frequently as a justification for not writing documentation. And while we should all strive for self-documenting code, the code is the truth, but not the whole truth. In this talk we'll look at the importance of technical documentation, and a powerful trio of lightweight artefacts that describe what you can't get from the code.