In this blog post, we will explore the internals of QObject and QMetaObject and discover how signals and slot work under the hood. In this blog. In this tutorial, we will learn QtGUI project with signal and slot mechanism. In Qt , we have an alternative to the callback technique: We use signals and slots. Mechanism to access any function in the class (used by signals and slots); Class to do the listener management yourself as this is done by the qt object system.