# Key Concepts A few terms come up everywhere in open.DASH. Understanding them makes the rest of the documentation much easier to follow. ## Data sources and sensors A **data source** is a system, machine, or connector that delivers data into the platform (for example a PLC, an API, or a manual input form). Each data source exposes one or more **sensors** — the individual measurements it provides, such as a temperature, a counter, a machine state, or a GPS position. Every sensor value has a **type** (Number, String, Boolean, Geo, or Object). The type tells open.DASH how the value can be displayed and aggregated — for example, only numeric values can be shown on a gauge, and only Geo values can be placed on a map. ## Dashboards A **dashboard** is a page that collects several widgets in a layout you control. You can create as many dashboards as you like — for example one per machine, line, or team — and arrange, resize, and reorder the widgets on each. ## Widgets A **widget** is a single tile on a dashboard. Each widget takes one or more sensors as input and presents them in a particular way: a line chart, a table, a KPI tile, a map, and so on. open.DASH ships with a large library of widgets; browse them all in the **[Widget manuals](Widget%20Manuals.md)**. ## The Data Sidebar The **[Data Sidebar](Data%20Sidebar.md)** is your catalogue of everything available to you. It lists all data sources and sensors, with their current values and the time of the last update — useful whenever you are unsure which sensor to pick. ## The Data Explorer The **[Data Explorer](Data%20Explorer.md)** is the guided way to build a widget: first you choose *which* data and *what* time range, then you choose *how* to display it. open.DASH only offers visualizations that fit the selected data types. ## Modules open.DASH is the dashboarding entry point of a larger ecosystem. Other **modules** plug into the same platform — for example **open.SERVICE** for maintenance, **open.CONNECT** for data collection, and **open.CHECK** for shop-floor data capture. You will find these under *Modules* in the sidebar.