# PPerl Architecture

How pperl is built, what sets it apart from upstream Perl 5, and the
subsystems a working programmer reaches for when they want more than
”run this Perl script“ — the JIT, the FFI, the native-module layer,
and the dual runtime.

This guide is descriptive, not a tutorial. Read it to understand
*how* pperl does what it does and *why* certain things behave the
way they do. Per-function behaviour lives in the
[reference tree](../../p5/index.md).

* [Runtimes](runtimes.md)
* [JIT Compilation](jit.md)
* [Auto-FFI (Peta::FFI)](ffi.md)
* [Native Modules](native-modules.md)
* [Differences from Perl 5](differences-from-upstream.md)