---
title: "Stage 2, Send: a collector moves your spans | Grafana Labs"
description: "How a collector receives spans and forwards them, and why trace volume needs sampling."
---

> For a curated documentation index, see [llms.txt](/llms.txt). For the complete documentation index, see [llms-full.txt](/llms-full.txt).

## Stage 2, Send: a collector moves your spans

Your instrumented application doesn’t write straight to storage. The spans first pass through a piece of software that receives them and forwards them on to a backend. That piece is a **collector**.

Grafana’s collector is **Grafana Alloy**. Alloy receives the spans your application emits and forwards them to a tracing backend. It speaks **OTLP** (OpenTelemetry Protocol), the standard format for sending telemetry data.

## Traces add up fast

Tracing produces a higher volume of data than metrics. A single request can create dozens or hundreds of spans, and that volume grows with your traffic, so traces are one of the easiest signals to over-ingest. To keep the volume, and the cost, manageable, you keep a representative subset of traces instead of all of them, a practice called **sampling**. Choosing a sampling strategy is part of setup, covered in the setup journey.