Provides the fundamental synchronization primitives, including System.Threading.Monitor and System.Threading.Mutex, that are required when writing asynchronous code. Commonly Used Types: System.Threading.Monitor System.Threading.SynchronizationContext System.Threading.ManualResetEvent System.Threading.AutoResetEvent System.Threading.ThreadLocal<T> System.Threading.EventWaitHandle System.Threading.SemaphoreSlim System.Threading.Mutex When using NuGet 3.x this package requires at least version 3.4.