Описание тега qtcore
Questions related to the QtCore module that provides core non-graphical classes used by other modules.
If you use qmake to build your projects, Qt Core is included by default.
Official documentation.
Tagging recommendation:
Add this tag to questions when the issue at hand is related to the classes provided by this module. There are already several class tags for those, so you should add them, too.
The purpose of this is to provide a container for a better overview about the questions related to the core functionality.
Typically, this tag can be seen together with tags like qstring, qobject, qt-signals, qfile, qiodevice, qvector, qlist, qtextstream, qthread, qsettings, et al.