Platform Invocation Services
Platform Invocation Services, commonly referred to as P/Invoke, is a feature of Common Language Infrastructure implementations, like Microsoft's Common Language Runtime, that enables managed code to call native code. Managed code, such as C# or VB.NET, provides native access to classes, methods, and types defined within the libraries that make up the .NET Framework.
Source: Wikipedia — Platform Invocation Services (CC BY-SA 4.0)