Observability as a concept that explains to what extent a network or an environment can be perceived with the help of data gathered from external sources contributed by the environment itself.
Monitoring deals with "known unknowns" while observability deals with "unknown unknowns." Observability is surveilling your environment to avoid the above-mentioned anomalies and predicting changes, if any.
Observability gives you superior control over complex networks and distributed systems that are unpredictable or dynamic in nature. A fully observable network will facilitate and simplify the flow of processes. This includes service deployment, configuration changes, workload distribution, cloud dependency, customer experience, service performance, and resource consumption.
Observability uses telemetry data to determine the behavior of an environment. Telemetry data gathered through metrics, logs, and traces, commonly known as the three pillars of observability, is then employed to achieve a fully observable environment.