Observability has rapidly become a cornerstone of modern engineering strategies, though its definition has been hotly debated recently.
With its roots in control systems theory, observability was popularized by the Honeycomb team in 2016. They expanded upon Rudolf E. Kálmán’s definition — “a measure of how well internal states of a system can be inferred from knowledge of its external outputs.” — and redefined it to mean “the power to ask new questions of your system, without having to ship new code or gather new data to ask those new questions.”
(TNS)