Docs to clarify what various components are used for

docs/sources/flow/reference/components/_index.md

@@ -14,6 +14,96 @@ weight: 300
 
 This section contains reference documentation for all recognized [components][].
 
+## Which component do I need?
+
+### Receiving telemetry
+
+##### Logs
+
+* In the Loki format: `loki.source` components such as `loki.source.file`.
+  * If you need to convert from the Loki format to OTLP, you can use `otelcol.receiver.loki`.
+* In the OTLP format: some `otelcol.receiver` components, such as `otelcol.receiver.otlp`.
+
+##### Metrics
+
+`prometheus.scrape` scrapes HTTP endpoints using the Prometheus exposition format.
+
+`prometheus.receive_http` accepts metrics in the Prometheus format on a HTTP server.
+  A separate process such as {{< param "PRODUCT_ROOT_NAME" >}}, Prometheus, or OpenTelemetry Collector could remote write ("push") metrics on this server.
+
+##### Traces
+
+* In the OTLP format: some `otelcol.receiver` components such as `otelcol.receiver.otlp`.
+
+##### Profiles
+
+`pyroscope.scrape` scrapes profiles from HTTP endpoints using the Pprof format.
+
+### Processing telemetry
+
+#### Logs
+
+All `loki.source` components can receive logs, in the Loki format. If you need to convert from the Loki format to OTLP, you can use `otelcol.receiver.loki`.
+
+##### Metrics
+
+* In the Prometheus format: `prometheus.relabel`.
+* In the OTLP format: `otelcol.processor` components such as `otelcol.processor.transform`.
+
+##### Traces
+
+* In the OTLP format: `otelcol.processor` components such as `otelcol.processor.transform`.
+
+##### Profiles
+
+At this time, profiles can only be received and sent by {{< param "PRODUCT_ROOT_NAME" >}}.
+
+### Sending telemetry
+
+##### Logs
+
+All `loki.source` components can receive logs, in the Loki format. If you need to convert from the Loki format to OTLP, you can use `otelcol.receiver.loki`.
+
+Some `otelcol.receiver` components such as `otelcol.receiver.otlp` can also receive logs, in the OTLP format.
+
+##### Metrics
+
+In the Prometheus format: `prometheus.remote_write`.
+
+In the OTLP format: `otelcol.exporter` components such as `otelcol.exporter.otlp`.
+
+##### Traces
+
+* In the OTLP format: `otelcol.exporter` components such as `otelcol.exporter.otlp`.
+
+##### Profiles
+
+`pyroscope.write` sends profiles using Pyroscope's Push API.
+
+### Converting one telemetry type to another
+
+`loki.process` can create metrics out of logs using the `stage.metrics` block.
+
+`otelcol.connector` components generally output a different type of telemetry from the one that they input.
+For example, `otelcol.connector.spanmetrics` creates RED OTLP metrics from OTLP traces.
+
+Converting metrics from the native Prometheus format to OTLP can be done using `otelcol.receiver.prometheus`.
+To convert OTLP metrics to Prometheus, use `otelcol.exporter.prometheus`.
+
+Converting logs from the native Loki format to OTLP can be done using `otelcol.receiver.loki`.
+To convert OTLP metrics to Prometheus, use `otelcol.exporter.loki`.
+
+### Configuring {{< param "PRODUCT_ROOT_NAME" >}} dynamically 
+
+The Agent can receive part of all of its configuration dynamically, via `module` components such as `module.file`.
+`module.git` pulls AGent configuration from a Git repository, whereas `module.http` pulls it from an HTTP endpoint.
+
+### Other components
+
+`mimir.rules.kubernetes` discovers `PrometheusRule` Kubernetes resources and loads them into a Mimir instance.
+
+## All components
+
 {{< section >}}
 
 [components]: {{< relref "../../concepts/components.md" >}}