What is Cygwin?
Cygwin is a collection of open source tools that allows Unix or Linux applications to be compiled and run on a Microsoft Windows operating system (OS) from within a Linux-like interface. Cygwin offers users a Linux-like experience in a Windows environment. This capability helps developers migrate applications from Unix or Linux to Windows-based systems and makes it easier to support their applications running on the Windows platform.
At the heart of the Cygwin collection of tools is the cygwin1.dll dynamic link library (DLL). The DLL serves as an emulation layer that provides Portable OS Interface, or POSIX, system call functionality. The Cygwin distribution also has a large collection of free tools, including most GNU and many Berkeley Software Distribution tools, along with an X server and a full set of X applications.
The name Cygwin was created from a combination of Cygnus and Windows.