Node-RED is a visual programming tool for wiring together hardware devices, APIs and online services, especially for the Internet of Things (IoT). It provides a browser-based editor that makes it easy to wire together flows using the wide range of nodes in the palette.
For example, a Node-RED flow could be used to connect a temperature sensor to the cloud and send an email alert when the temperature reaches a certain threshold. The flow would include nodes for the temperature sensor, a cloud service, and an email service, and the connections between them. It would then be possible to configure each node with the relevant settings and create a flow that would automatically send an email when the temperature reaches the threshold.