In this Qt6 video we are going to learn about Signals & Slots with Qt6 Designer, Qt6 Signals and Slots is a mechanism for communication between objects in the Qt6 framework. it allows objects to communicate with each other by emitting signals and receiving them through slots. this mechanism is an essential part of the Qt6 framework, as it provides powerful way to design and implement complex applications. in Qt6 signal is a function that is emitted when  particular event occurs. for example a button may emit a signal when it is clicked. slot is a function that is called in response to a signal. for example a slot may be used to update  display when a button is clicked. signals and slots mechanism provides several advantages over traditional callback functions:

1. Loose Coupling: objects that emit signals do not need to know about the objects that receive them. this allows for loose coupling between objects which makes it easier to modify or replace objects without affecting the rest of the application.
2. Automatic Connection: Qt6 provides automatic connection between signals and slots, which means that developers do not need to write any code to connect them. this makes it easier to create complex applications with many objects communicating with each other.
3. Thread-Safety: Signals and slots are thread safe which means that they can be used in multi threaded applications without the need for additional synchronization code.
4. Extendibility: Signals and slots can be extended using inheritance which allows developers to create custom signals and slots that meet their specific requirements.

For using signals and slots in Qt6 application developers need to define signals and slots in their objects and connect them using the connect() function. connect() function takes signal,  slot and an optional connection type as parameters. connection type specifies how the signal and slot should be connected such as whether the connection should be one time or continuous.

in summary Qt6 Signals and Slots is a powerful mechanism for communication between objects in the Qt6 framework. it provides loose coupling, automatic connection, thread safety, and extendibility, making it an essential part. (Signals & Slots with Qt6 Designer)