Default apps
Psibase comes with default applications that bootstrap the initial functionality of the network. Ultimately, all of this functionality is customizeable by modifying the app code.
System apps
System apps are the applications responsible for the core functionality of the network. Changing these applications could drastically alter fundamental properties about the network.
Additional apps
Psibase also comes with various apps meant to demonstrate additional functionality. These additional apps can be removed or replaced by other custom apps without upsetting any of the core functionality of the network.