AWT (the abstract window toolkit) is a GUI library that comes with Java. I talked about it at the top of the Swing tutorial:
But basically, AWT contains a bunch of classes that let you build a GUI. Stuff like
Applet. Before Processing 3, the
PApplet class extended the
Applet class, so you could treat Processing like any other AWT applet: you could embed it in a website, or directly into a Java application.
But as of Processing 3, the
PApplet class no longer extends the
Applet class. That means you can’t embed it as a component in a Java application.
However, Processing still uses AWT behind the scenes. The only thing that changed is that
PApplet no longer extends
Swing is another GUI library that comes with Java, and it’s built on top of AWT. I’d recommend reading through the Swing tutorial above for more background.
In fact, Processing uses a mix of AWT and Swing behind the scenes, if you’re using the default renderer. But the beauty of Processing is that you don’t have to really worry about any of this.