In this reference guide, you'll learn more about the intricacies of the signal & slot concept in PyQt. This concept is very important when dealing with GUI development and while it's beautifully solved by Qt, it can be a little confusing in the beginning.
Our second tutorial in the QGIS plugin development series focuses on QGIS and user interaction. You will learn how capture a point clicked on the map canvas by the user, a few practical examples of the concept of signals & slots in PyQt, and then some more.
This post provides a basic reference guide for plugin development in QGIS v3. It describes the most important concepts around QGIS plugins, which a developer should be aware of, such as mandatory methods expected by QGIS, detailed explanation of the output of Plugin Builder 3 and more.