A region is a type of agent which represents 2D areas on the Playfield. A region consists of cells which can eithor be added or cleared from it. To make interaction easier, rects can be used to represent cells in a rectangular area when manipulating a region.
regions, rects and GUI confusion
When editing in GUI or in the Regions Layer, rects are falsely referd to as regions. This has lead to a lot of beginners getting confused as to what they are. The Regions Layer produces rect objects and regions in GUI are actually rects, these are totally different from actual region objects and are not interchangeable as far as use.