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

# Overview

> What Odigos VM Agent instrumentation rules are, their benefits, and rule types: code attributes, headers collection, payload collection, and custom instrumentation.

Instrumentation rules control how telemetry is recorded from your [sources](../../../overview#key-concepts). You can apply rules to specific sources and instrumentation libraries to control which attributes, headers, and payloads are collected and how custom instrumentations behave.

## Benefits

* **Control what is recorded** — Decide which code attributes, HTTP headers, and payloads are added to spans so you capture the right context without excess volume.
* **Enrich without code changes** — Get better context without modifying or redeploying your application.
* **Trace back to code** — Code attributes link spans to the code that produced them, so you can debug and analyze with confidence.
* **Custom instrumentation** — Define custom eBPF-based instrumentations for arbitrary functions in your application or its dependencies.

## Rule types

You can manage instrumentation rules via [odictl](../odictl) or YAML.

### Custom instrumentation

Define custom eBPF-based instrumentations for arbitrary functions in your application or its dependencies. Use custom instrumentation with Java and Go applications to instrument application-specific code. See [Custom Instrumentation](./custom-instrumentation) for configuration.

### Code attributes

Add [semantic code attributes](https://opentelemetry.io/docs/specs/semconv/attributes-registry/code/) to spans so you can trace an operation back to the code that generated it.

<Info>
  **Planned for a future release.**
</Info>

### Headers collection

Add span attributes by collecting HTTP header data from requests and responses.

<Info>
  **Planned for a future release.**
</Info>

### Payload collection

Add span attributes by collecting payload data from HTTP requests and responses, database queries, and messaging systems.

<Info>
  **Planned for a future release.**
</Info>