Wikipedia
qmake is a utility that automates the generation of Makefiles. Makefiles are used by the program make to build executable programs from source code; therefore qmake is a make-makefile tool, or makemake for short.
The Makefiles that qmake produces are tailored to the particular platform where it is run from based on qmake project files. This way one set of build instructions can be used to create build instructions on different operating systems. qmake supports code generation for the following operating systems: Linux, Apple Mac OS X, Symbian, Microsoft Windows and Microsoft Windows CE.
qmake was created by Trolltech (now owned by Digia), and is distributed along with the Qt toolkit. It integrates with the Qt framework, and automates the creation of moc (meta object compiler) and rcc (resource compiler) sources, which are used in Qt's meta-object system and in the integration of binary resources (e.g. pictures).