The BCL is the library of types (classes, interfaces, structures) included with the runtime. It provides the fundamental building blocks for applications, including:
The Microsoft .NET Runtime, also known as the .NET Common Language Runtime (CLR), is a runtime environment that hosts and manages .NET applications. It provides a set of services and libraries that enable .NET developers to build a wide range of applications, from web and mobile apps to desktop and server-based systems. microsoft .net runtime
Converts Intermediate Language (IL) code—the format your program is compiled into—into machine-specific instructions right before it runs. The BCL is the library of types (classes,