When C became the lingua franca for systems and application programming, compiler vendors wrapped common functionality into runtime libraries. These runtimes provided consistent implementations of the C standard library—functions like printf, malloc, fopen, and strcmp—and handled startup and shutdown chores for C and C++ programs. Microsoft’s runtime evolved from this tradition, first as part of its C compiler toolchains for MS-DOS and then as a core part of Microsoft Visual C++ for Windows.
When you write standard C code using functions like printf , malloc , or strcmp , you are not calling Windows APIs directly. Instead, you are calling CRT functions, which then handle the underlying interactions with the OS kernel. microsoft c runtime
The CRT is not a single file. Over the years, Microsoft has evolved its packaging, linking models, and security features in response to application deployment needs, performance demands, and the complexity of the Windows ecosystem. When C became the lingua franca for systems