Provides classes that help you trace the execution of your code. Developers should prefer the classes in the ETW-based System.Diagnostics.Tracing package. Commonly Used Types: System.Diagnostics.TraceListener System.Diagnostics.TraceLevel System.Diagnostics.TraceSource System.Diagnostics.TraceEventType System.Diagnostics.DefaultTraceListener System.Diagnostics.Trace When using NuGet 3.x this package requires at least version 3.4.