What the runtime is (and why it matters) At its core, the Visual C++ runtime delivers implementations of the C and C++ standard libraries, runtime support for exception handling, memory allocation, thread-local storage, and ABI glue that ties compiled C++ binaries to the operating system. For developers using Microsoft’s toolchain (MSVC), the runtime is the shared underpinning that allows multiple applications compiled with the same toolset to reuse common code rather than bundling duplicate copies into every executable or DLL.