The "bridge" is a term I had heard before finding Rock Singing Success. I had been told there is one bridge, also called a passaggio and that learning to navigate the passaggio well (think of Chris Isaak singing Wicked Game) is the key to being able to sing with tonal consistency from low notes to high notes and not have your voice crack while you're doing it. By tonal consistency, I just mean being able to sing throughout your range and not sound like one person in mode one and sound like somebody else in mode 2. Navigating the passagio meant being able to transition from mode one to mode two seamlessly. That may be valid information. I learned it even before I ever met my first vocal coach, so since it didn't come from him, its certainly possible that it's an accurate description of how what the "bridge" is: The thing that you use to move back and forth between modes one and two and not have your voice crack, or sound like two different singers. As far as I know, unless you want to count fry as "mode zero", there are just two modes. Mode one is what you typically use to speak, unless you're Mickey Mouse, and then there's mode two, which is also sometimes called head register. The voice breaks if you're not skilled in navigating the passaggio. I had gathered that you could think of the passaggio as the "bridge" that takes you from mode one into mode two. This was my understanding of "bridge" before I found RSS. R.S. found RSS. Imagine that! Good thing too, since the way I was being taught to create grit was pulverizing my larynx. "Just imagine you're lifting something heavy" - No thanks! If I were deliberately setting out to create as much unnecessary muscle tension as possible, then that would have been useful, but otherwise, no. There had to be a better way. "Just use the least amount of constriction necessary." - OK, I'm paraphrasing, but essentially that was what made RSS different from the way I was previously taught to create grit. My first coach encouraged me to constrict until no air at all was coming out and then just release tension ever so slightly until a little air can finally escape and we have "Grrrrrit"! And Reinke's Edema too!