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

# About Ably

Ably is a highly-scalable serverless WebSocket platform used to power realtime digital experiences.

At its core, Ably is a cloud-based Pub/Sub (publish/subscribe) platform-as-a-service (PaaS). It ensures that any messages published to Ably by any device will be received, in realtime, by any number of subscribing devices.

## Platform overview

Ably's platform enables data to be streamed between all internet-connected devices, such as browsers, servers and mobile phones. It offers enterprise-scale messaging that automatically scales to meet demand, a highly-available service, message delivery guarantees, and low latency across the globe.

Ably is engineered around the following four key principles to ensure the dependability of its service:

<CardGroup cols={2}>
  <Card title="Performance" icon="gauge-high">
    High performance ensures that the end-to-end latency and bandwidth for data sent via the platform is minimized, and maintained at scale.
  </Card>

  <Card title="Integrity" icon="shield-check">
    Provides guarantees for the realtime messages sent using the Ably platform so that you don't need to handle missed, duplicated or unordered messages yourself.
  </Card>

  <Card title="Reliability" icon="server">
    A fault-tolerant platform is reliable by ensuring that there is sufficient redundancy at a regional and global level to provide continuity of service in the face of infrastructure failures.
  </Card>

  <Card title="Availability" icon="circle-check">
    The Ably platform is designed to be elastic and highly-available so that you can use it at any time, even under high load.
  </Card>
</CardGroup>

## Core capabilities

### Enterprise-scale messaging

Ably serves billions of devices monthly and delivers over half a trillion messages monthly. The platform is built to handle massive scale while maintaining consistent performance and reliability.

### Automatic scaling

The platform automatically scales to meet demand, ensuring that your applications can grow without infrastructure constraints. Resources are provisioned on demand as load changes, eliminating the need for capacity planning.

### Message delivery guarantees

Ably provides:

* **Exactly-once delivery semantics**: Messages are delivered once and only once to subscribers
* **Guaranteed message ordering**: Messages arrive in the order they were published
* **100% message delivery guarantee**: Through multi-region redundancy, Ably ensures messages are never lost
* **99.999999% message survivability**: Statistical guarantee for message availability

### Global low latency

Ably achieves a global mean latency of 37ms, with:

* `<30ms` round trip latency within datacenter (99th percentile)
* `<65ms` global round trip latency (99th percentile)

### High availability

The platform is designed for:

* **99.999% global service availability**: Only 5 minutes 15 seconds of downtime per year
* **50% global capacity margin**: For instant demand surges
* **Automatic failover**: Edge network failure resolution within 30 seconds

## Global network

For detailed information about Ably's global infrastructure:

* View the [network map](https://ably.com/network) of Ably's datacenters and global points of presence
* Check the [status of datacenters](https://status.ably.io/) by region
* See [global round-trip latency statistics](/docs/platform/architecture/latency) measured externally

## Next steps

<CardGroup cols={2}>
  <Card title="Infrastructure" href="/docs/platform/infrastructure">
    Learn about Ably's global infrastructure and edge network
  </Card>

  <Card title="Security" href="/docs/platform/security">
    Understand Ably's security measures and encryption
  </Card>

  <Card title="Architecture" href="/docs/platform/architecture/edge-network">
    Explore Ably's platform architecture in detail
  </Card>

  <Card title="Products" href="/docs/platform/products">
    Discover Ably's products and SDKs
  </Card>
</CardGroup>