Start here. This is the direct spoken answer to practice first.
Overview
Micrometer Observation provides one instrumentation lifecycle that different handlers can turn into metrics, traces, logs, or other signals.
A Micrometer Observation represents an operation such as an HTTP request or service call. It is created through an ObservationRegistry, started, optionally scoped, and then stopped with an outcome. Registered handlers react to that lifecycle; one handler can record metrics while another creates tracing spans. Spring Boot configures much of this instrumentation automatically when Actuator and the relevant registry or tracing bridge are present.