> ## Documentation Index
> Fetch the complete documentation index at: https://docs.goakt.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# First Actor

> Create your first actor system, spawn an actor, and send messages.

This guide walks through the flow of creating an actor system, spawning an actor, and sending messages. For the full ActorSystem API and configuration, see [Actor System](/actor/actor-system).

## Flow

1. **Create** an actor system with `NewActorSystem` and `Start`
2. **Spawn** an actor with `Spawn(ctx, name, actor)` → receive a `*PID`
3. **Send** messages with `NoSender().Tell` (fire-and-forget) or `NoSender().Ask` (request-response)
4. **Shutdown** with `Stop` when the application exits

## Actor interface

Implement the `Actor` interface to define your actor. See [Actor Model](/actor/actor-model#the-actor-interface)
for the full interface and method explanations.

## Messaging from outside

From outside the actor system (e.g., `main`), use `NoSender()` to send:

* **Tell** — Fire-and-forget. No response expected.
* **Ask** — Request-response. Blocks until reply or timeout. The actor must call `ctx.Response(resp)` to complete the
  request.

## Replying from an actor

When handling a message sent via `Ask`, call `ctx.Response(resp)` exactly once. The caller receives that value. For
`Tell`, no reply is expected.

## ReceiveContext

Inside `Receive`, `ctx` provides:

| Method                  | Purpose                                                  |
| ----------------------- | -------------------------------------------------------- |
| `Message()`             | The message being processed                              |
| `Sender()`              | PID of the sender (nil for scheduled or system messages) |
| `Self()`                | PID of the current actor                                 |
| `Tell(to, msg)`         | Send fire-and-forget to another actor                    |
| `Ask(to, msg, timeout)` | Send request-response                                    |
| `Response(resp)`        | Reply to an Ask                                          |
| `Unhandled()`           | Mark message as unhandled                                |

For more examples, see the [goakt-examples](https://github.com/Tochemey/goakt-examples) repository.