This document discusses the evolution of observability from network/device monitoring (Wave 1) to application performance monitoring (Wave 2) to the current focus on observability (Wave 3). It notes that observability moves past proprietary data formats and interdependence of early solutions by enabling instrumentation once and observation anywhere. The document advocates for teams to own end-to-end observability of their services and dependencies, and notes that observability data can help teams understand where to invest engineering time to most directly impact customers and business goals.