OTP

OTP (Open Telecom Platform) is a collection of tools and libraries for building fault-tolerant, scalable and concurrent systems in Erlang.

It was originally developed at Ericsson, a telecom company.

Elixir runs on the Erlang VM (BEAM) and it can fully leverages OTP as well.

The Actor Model

Like Erlang, Elixir uses the Actor Model. In the Actor Model, actors are the fundamental units of computation.

An actor is an independent, self-contained entity with its own state. There is no shared state between the actors.

An actor can change its internal state and can send messages to and receive messages from other actors.

An actor can also create new actors.

Because actors work independently and interact only by passing messages, this approach make it much easier to write highly concurrent and fault-tolerant systems.