The Application module provides classes commonly needed at program startup and runtime:

PICLI — command-line argument parser. Add named arguments (e.g. addArgument("debug") for -d / --debug), check presence with hasArgument(), optionally read values. Used in Getting started for console and debug flags.
PILog — high-level logging with categories and levels. Configure sinks and severity; write log lines from anywhere in the process.
PISystemMonitor — snapshot of system resources (CPU, memory, etc.). Query current stats or subscribe to periodic updates.
PISingleApplication — ensure only one instance of the application runs; optional inter-process messaging when a second instance is started.
PITranslator — translation support: load catalogs, select language, translate strings at runtime.

All are included via the main PIP library or the Application umbrella (piapplicationmodule.h). For CLI and logging, see Getting started; for full API details see the headers picli.h, pilog.h, pisystemmonitor.h, pisingleapplication.h, pitranslator.h.