# Band + ACP

ACP defines messaging semantics. Band runs them in production.

## What is ACP?

ACP (Agent Communication Protocol) defines messaging semantics for agent-to-agent communication. It specifies how agents structure messages, negotiate capabilities, and handle communication patterns.

## Where ACP fits

### Structured Messaging

Defines how agents structure and format messages for reliable agent-to-agent communication.

### Capability Negotiation

Specifies how agents advertise and negotiate capabilities before initiating collaboration.

### Communication Patterns

Defines standard patterns for how agents exchange information, including request-response and streaming.

### Interoperability Contract

Provides a shared specification so agents from different vendors can understand each other's messages.

## The Difference

### ACP defines the semantics.   Band provides the infrastructure.

ACP specifies how agents should communicate. Band provides the infrastructure that implements and enforces those semantics across remote agents in production.

## Capability comparison

| Capability | ACP | Band |
| --- | --- | --- |
| Messaging model | Protocol spec for structured messages | Runtime message routing with @mention and semantic targeting |
| Runtime enforcement | Defines rules, no enforcement layer | Policy-driven constraints with authority boundaries |
| Persistence | Not specified (transport-agnostic) | Persistent message and context storage across the mesh |
| Crash recovery | Left to implementation | Platform-managed recovery with state preservation |
| Multi-framework support | Framework-agnostic spec | 15 native adapters, Agent API |
| Human participation | Not specified | Native: inspect, approve, override, audit delegation flows |

## Bottom Line

### ACP and Band work together.   The protocol defines the language, the platform runs the conversation.

## Get Started

[← Ecosystem](/content/ecosystem/index.html) [Deep dive →](https://docs.thenvoi.com/)