# Pyro4 library API

This chapter describes Pyro’s library API. All Pyro classes and functions are defined in sub packages such as `Pyro4.core`, but for ease of use, the most important ones are also placed in the `Pyro4` package scope.

- `Pyro4` — Main API package
- `Pyro4.core` — core Pyro logic
- `Pyro4.naming` — Pyro name server
- `Pyro4.util` — Utilities and serializers
- `Pyro4.socketutil` — Socket related utilities
- `Pyro4.message` — Pyro wire protocol message
- `Pyro4.constants` — Constant value definitions
- `Pyro4.config` — Configuration items
- `Pyro4.errors` — Exception classes
- `Pyro4.test.echoserver` — Built-in echo server for testing purposes
- `Pyro4.utils.flame` — Foreign Location Automatic Module Exposer
- `Pyro4.futures` — asynchronous calls
- Socket server API contract