Sources Overview

A source is a website, server library, mobile SDK, or cloud application which can send data into Segment. It's where your data originates. Add a source to collect data to understand who your customers are and how they're using your product. Create a source for each website or app you want to track. While it's not required that you have a single source for each server, site, or app, you should create a source for each unique source of data.

Each source you create has a write key, which is used to send data to that source. For example, to load analytics.js, the Segment JavaScript library on your page, the snippet on the Quickstart Guide includes:

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analytics.identify("user_123", {
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  email: "jane.kim@example.com",
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  name: "Jane Kim",
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});

Segment has three types of sources:

• Event streams
• Cloud app sources
• Reverse ETL

Event streams sources collect data from your website or app to monitor user actions. These sources include website libraries, mobile and server sources.

The Source Overview page for an event stream source shows you:

• A pipeline view of all events Segment receives from your source,
• Events that failed on ingest,
• Events that are filtered at the source level,
• "Eligible events", which are the events that will flow into your destinations. If you select one of the steps in the pipeline view, you can see a line chart that reflects the fluctuations in volume alongside a breakdown table that has more details about the events impacted by the selected step.

The pipeline view shows each of the four steps Segment encounters when processing data from your source:

• Events successfully received: All events that Segment received from your source.
• Failed on ingest: Events that failed at the Tracking API level. For more information about errors that might cause events to fail on ingest, see Delivery Overview's Troubleshooting documentation.
• Filtered at source: Events that were filtered out by source schema controls, Tracking Plans, or a common JSON schema.
• Eligible events: Eligible events are the events that flow downstream to your Segment destinations. This value is read-only, but you can see the events that flow downstream to a particular destination using Delivery Overview.