An actor ... in response to a message it receives, can concurrently:
- send a finite number of messages to other actors;
- create a finite number of new actors;
- designate the behavior to be used for the next message it receives. 
Actors make concurrency easy to understand and reason about and integrate well with Julia's multi-threaded and distributed computing.
Actors provides a modern API  for writing reactive  applications, that are:
- responsive : react to inputs and events,
- resilient : can cope with failures,
- elastic : can distribute load over multiple threads and workers,
- message-driven : rely on asynchronous message-passing.
This overview of
Actors' documentation  will help you know where to look for certain things:
- Tutorials will help you to learn how to work with actors. Start here if you’re new to
- How-to guides are recipes. They guide you through the steps involved in addressing key problems and use-cases. They are more advanced than tutorials and assume some knowledge of how actors work.
- On Actors discusses key concepts and provides background information and explanation.
- Reference contains technical reference for APIs, some examples and internals. It assumes that you have a basic understanding of key concepts.