"Front" is a place in our head that's like a doorway right through the shared-body's eyes. Front was one of our first internal landscape interfaces that we recognized.
We have early poems that refer to Front as a door or window, and to the inside of our head being a deeply shadowed room. When (external) people look deeply into our eyes, they are looking through the doorway and into us.
"Front" gives way to other terminology we've always used, such as "in Front" or "Fronting" for someone inside who is looking directly through our eyes to external reality, and "Front Room" which is the internal room where the "Front" doorway is. The person who "is front" or "is fronting" is the one currently in the doorway.
Most of Frank's ComiXes depict who is in the Front doorway during an internal landscape interaction. They're all from the point of view of someone internal, not the person actually in Front.
Front has a direct interface with the Control panel. Someone can be both Front and "in Control" or someone can Front and someone else be in Control or share Control with the person(s) fronting.