# The Source Picker The **source picker** sits in the **top-right corner of the header** and is one of the most important controls in open.DASH. It lets you choose which **source** you are currently looking at. ![open.DASH sourcepicker](../../../_attachments/opendash/sourcepicker.png) ## What is a source? A **source** is a data source organized in a hierarchy — for example `Company → Site → Line → Machine`. Each source groups the sensors and values that belong to it. (See [Key Concepts](Key%20Concepts.md) for the difference between sources and sensors.) The source picker shows this hierarchy as an expandable, **searchable tree**: - Expand a node to drill down from higher-level groupings to individual machines or areas. - Start typing to **search** for a source by name instead of scrolling through the tree. - Click a source to select it. On a desktop the picker is shown inline in the header; on smaller screens it appears as a button that opens a drawer. ## What selecting a source does Choosing a source sets the **current source** for the whole application — think of it as "which machine/site am I currently looking at?". The most visible effect is in **Monitoring**: dashboards can be **bound to a source**, so when you switch the source, open.DASH shows the dashboards that belong to the newly selected source. This means one dashboard layout can be reused across many machines — you build it once and simply switch the source to see the same view for a different machine. The selected source is also part of the dashboard's URL, so you can bookmark or share a link to a specific source's dashboard. ## When the picker is not shown The source picker only appears when **sources are configured** in your instance. It can also be hidden on specific pages where a source context doesn't apply. If you don't see it, your instance may not use sources, or the current page has disabled it. ## Tips - Use the search box for large hierarchies instead of expanding every level. - The picker remembers your selection as you navigate, so dashboards stay in the context you chose. ## Related - [The Frontpage](The%20Frontpage.md) — where you start after logging in. - [Key Concepts](Key%20Concepts.md) — sources, sensors, dashboards, and widgets. - [The Data Explorer](Data%20Explorer.md) — build a visualization for the selected data.