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Say, you are installing a Python package for pyEnchant or crfsuite, etc. It fails to install and in the error trace it says some .bat (or .dll) file is missing.
A few forums suggest you install Visual Studio and a few others give work-arounds like cygwin, mingw, etc.
Why do some Python packages require Visual Studio?
Installation from source of CPython extension modules written in C requires a C compiler. Visual Studio provides one such compiler.
To avoid it, use binary installers such as these.
Also, due to licensing restrictions, an extension module may not install some dlls automatically and you have to install Visual Studio that provides these dlls manually.