Distributed tracing is a diagnostic technique that helps engineers localize failures andperformance issues within applications, especially those that may be distributed acrossmultiple machines or processes. This technique tracks requests through an applicationcorrelating together work done by different application components and separating it fromother work the application may be doing for concurrent requests. For example, a request to atypical web service might be first received by a load balancer, then forwarded to a web serverprocess, which then makes several queries to a database. Using distributed tracing allowsengineers to distinguish if any of those steps failed, how long each step took, and potentiallylogging messages produced by each step as it ran.

Getting started for .NET app developers

Key .NET libraries are instrumented to produce distributed tracing information automatically. However, this information needs to be collected and stored so that it will be available for review later.Typically, app developers select a telemetry service that stores this trace information for them andthen use a corresponding library to transmit the distributed tracing telemetry to their chosenservice:

• OpenTelemetryis a vendor-neutral library that supports several services. For more information, seeCollect distributed traces with OpenTelemetry.
• Application Insightsis a full-featured service provided by Microsoft. For more information, seeCollect distributed traces with Application Insights.
• There are many high-quality third-party application performance monitoring (APM) vendors that offer integrated .NET solutions.

For more information, seeUnderstand distributed tracing concepts and the following guides:

• Collect distributed traces with custom logic
• Adding custom distributed trace instrumentation

For third-party telemetry collection services, follow the setup instructions provided by the vendor.

Built-in activities emitted by .NET

For a comprehensive list of activities built into .NET seeBuilt-in activities in .NET.

Getting started for .NET library developers

.NET libraries don't need to be concerned with how telemetry is ultimately collected, onlywith how it is produced. If you want consumers of your library to be able to see the work that it does detailed in a distributed trace, add distributed tracing instrumentation to support it.

For more information, seeUnderstand distributed tracing concepts and theAdding custom distributed trace instrumentation guide.