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

# Spans

> A span is the smallest unit of captured work inside a trace, such as an LLM call, a tool call, or a retrieval step.

# Spans

A **span** is the smallest unit of captured work in Latitude. Each span represents one operation inside an agent run: an LLM call, a tool call, a retrieval step, an HTTP request, or any custom operation you instrument. One or more spans make up a [trace](./traces).

## What a span captures

A span can record:

* input and output content, when available
* start time, end time, and duration
* success or error status
* tags and metadata
* provider, model, token usage, and cost for LLM calls

## Common span kinds

* **LLM call**: a request to a model, with its prompt, response, token usage, and cost.
* **Tool call**: a function or tool the agent invoked, with its input arguments and result. See [Tool calls](./tool-calls).
* **Retrieval**: a lookup against a vector store, database, or search index.
* **HTTP request**: an outbound call to an external service.
* **Custom**: any operation you instrument yourself.

## How spans form a trace

Spans nest to show the execution path of a single interaction, and a trace groups them into one complete interaction:

```text theme={"theme":{"light":"github-light","dark":"github-dark"}}
Trace: user turn
├─ Span: retrieve context
├─ Span: LLM call
└─ Span: tool call
```

Open any trace to see its spans as a tree, then expand a span to inspect its input, output, timing, and status. Use spans when you need to understand exactly what happened inside a trace, such as where latency, cost, or an error came from.

## Next steps

* [Traces](./traces): the complete interaction a span belongs to
* [Tool calls](./tool-calls): inspect the tools the agent called
* [Sessions](./sessions): group related traces into a conversation
* [Core Concepts](../getting-started/concepts): the full product vocabulary