The file `vcruntime140_1.dll` is a component of the Microsoft Visual C++ Redistributable for Visual Studio 2015, 2017, and 2019. This DLL is part of the Microsoft C Runtime Library and is essential for running applications developed with these versions of Visual Studio using the C++ programming language. The presence of the `_1` suffix in the file name `vcruntime140_1.dll` indicates an update or a specific version of the Visual C++ 2015-2019 runtime libraries, providing additional functionalities or bug fixes not present in the original `vcruntime140.dll`. This redistributable package includes runtime components of Visual C++ libraries that are required to run applications developed with Visual Studio in C++. These libraries help in distributing code that includes features from the standard C++ library, parallel programming support, and certain Microsoft extensions to the C++ language.

When C++ applications are developed, they often rely on the shared code within these DLLs to execute various functions and features. This shared model allows for efficient use of resources and reduces the application's size since the common code doesn't need to be included with every application. Instead, it's accessed through these shared DLLs. If `vcruntime140_1.dll` is missing or corrupt on a user's system, it can cause errors when attempting to run C++ applications that depend on it. The application might fail to start, or specific features within the application might not work correctly. Reinstalling the Microsoft Visual C++ Redistributable for Visual Studio 2015, 2017, and 2019 often resolves these issues by ensuring that the `vcruntime140_1.dll` and other necessary runtime components are correctly installed on the system.