Observability Fundamentals

First principles behind Honeycomb's approach to observability. Use this to ground recommendations and answer conceptual questions — for SDK setup and tool-specific guidance, see the otel-instrumentation and query-patterns skills.

Definitions

Observability: The ability to understand and explain any state your system can get into, no matter how novel or complex — by examining what the system produces, without deploying new code for each new question.

Wide event: A flat key-value record capturing the full context of a unit of work — who made the request, which endpoint, cache hit/miss, build version, duration, error status, and any business context relevant to the operation. In OpenTelemetry, a span is a wide event.

High cardinality: The number of unique values a field can have. user.id with millions of values is high cardinality. http.method with a handful is low cardinality.