What is the purpose of Span context?

The purpose of Span context is to link child spans to their parent trace. In distributed systems, transactions often involve multiple microservices or components that work together to complete a single request. Each operation within these components is represented as a span, which is a unit of work in distributed tracing.

By using Span context, each child span can maintain a reference to its parent span. This hierarchical structure is essential for constructing a trace, as it allows developers and observability tools to visualize and understand the flow of requests through various services. The parent-child relationship established through Span context helps in analyzing performance bottlenecks, identifying latencies, and troubleshooting issues effectively across complex systems.

The other choices, while related to application performance management and observability, do not directly describe the core purpose of Span context in the context of tracing and distributed systems. Error logs, metrics aggregation, and user session tracking serve different functions in monitoring and analysis but do not encompass the specific role of linking spans within a trace.