Flow Controller Nodes are responsible for manipulating the Flow Execution, like branching the flow in a number of different ways, filtering the flow, or even merging the flow. They are the means by which you create logic into your flowscript and correspond to the various scripting commands like if-then-else, while, for-each etc.

Flow Controllers have a purple title color and always have at least 1 Flow input and 1 Flow output port.

Each Flow Controller node being naturally different, has a help text in its inspector as all nodes do, to describe what it does.