Wine is a piece of software which lets Unix-like computer operating systems on the x86 and x86-64 architectures to execute programs written for Microsoft Windows. Wine runs Windows programs without using emulation. Wine also provides a software library known as "Winelib" which developers can compile Windows applications against to help port them to Unix-like systems. Some Wine code is used in ReactOS, a free operating system that is Windows-compatible and is not based on Unix.