---
title: "Vocabulary"
---
Words and definitions used across the IoT Atlas.  
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### Actuator
> an actuator is used to move or control a mechanism in the environment

### Command Message
> a [message](#message) describing an action that should be taken and that the device knows should be acknowledged on another topic once the action is complete.

### Device
> an entity that has enough power and compute resources to be a part of an IoT solution. Most often devices have [sensor](#sensor)s or [actuator](#actuator)s attached. 

### Device Data Density
> a device's data density is: `density = sample frequency * sample size * reporting frequency`

### Endpoint
> an endpoint is another name for a device, but often describing a device as an endpoint also implies the device operates on-premises with limited connectivity to the cloud

### Industry 4.0
> trend in manufacturing and automation to use IoT technology for connecting production assets to backend IT infrastructure (or cloud services) with the goal to extract data, gain finer grained control to production processes, allow predictions on quality and reduce downtimes ([Wikipedia](https://en.wikipedia.org/wiki/Industry_4.0))

### Limited Production
> effort to validate customer acceptance of the project's edge and cloud software at scale, in order to meet the majority of customer use-cases with a blueprint for mass production.

### Message
> a unit of communication in an IoT solution, often containing either sensed or command-related data

### Message Broker
> a component of an IoT solution responsible for managing message routing between authorized publishers and subscribers of topics.

### Message Topic
> a message topic, aka. *topic*, is a subject associated with a message. Topics are often used for the routing of messages from publishers to subscribers. In this context a message topic should be thought of as a direct map to the pub/sub concept of a subject and as a similar concept to the partial URLs used to describe request/response and REST endpoints.

### Ordered Store
> a data store or micro-service which fulfills the role in an IoT solution of ensuring that all records stored within it are in time-series order.

### Pilot
> effort performed to test a small set of customer use-cases, device configurations, and/or end-user features in order to identify a business outcome, software architecture, and/or create device blueprints.

### Production
> effort to mass produce devices and roll-out the IoT product to the market.

### Programmable Logic Controller
> ruggedized computing device or digital computer for industrial applications to monitor and control production/manufacturing processes ([Wikipedia](https://en.wikipedia.org/wiki/Programmable_logic_controller)).

### PLC
> abbreviation for [Programmable Logic Controller](#plc).

### Prototype
> effort taken for the purpose of education in order to obtain approval by a customer’s management to start the pilot phase.

### Rule
> a singular collection of logic and actions executed by a rules engine

### Rule Engine
> see Wikipedia ([Business rules engine](https://en.wikipedia.org/wiki/Business_rules_engine))

### Sensor
> a sensor is used to measure some aspect of the environment around it

### Trusted User
> Authenticated and authorized end user or installation technician, using a mobile/web app to configure the device in its deployed location.