In Qt, signals and slots are objects that allow communication between threads. A signal is a way to notify one or more threads of an event.
A slot is an object that allows a thread to wait for an event to occur.
Signals and slots can be used together to create powerful threading tools. For example, you can use a slot to wait for a particular signal to occur, or you can use a signal to notify a slot when an event has occurred.
When you create a signal or slot, Qt creates an object that participates in the Qt event loop. This object handles the actual communication between threads.
Using signals and slots is easy, and they provide powerful threading tools. If you need help using them, consult the Qt documentation.