Qt 4 consists of several modules, each of which lives in a separate library.
QtCore Core non-GUI classes used by other modules
QtGui Graphical user interface components
QtNetwork Classes for network programming
QtOpenGL OpenGL support classes
QtSql Classes for database integration using SQL
QtSvg Classes for displaying the contents of SVG files
QtXml Classes for handling XML
QtDesigner Classes for extending Qt Designer
QtUiTools Classes for handling Qt Designer forms in applications
QtAssistant Support for online help
Qt3Support Qt 3 compatibility classes
QtTest Tool classes for unit testing
If you use qmake to build your projects, the QtCore and QtGui modules are included by default. To link only against QtCore, add the following line to your .pro file:
QT -= gui