The bridge is the interface to the cartridge, sometimes called "that thingy bump whatsit". The bridge touches the cartridge filler and contains one end of the wick. The other end of the wick goes
through the coil. So the bridge-wick part is what transports the
juice to the coil so it can be heated to a vapor state.
Some folks just drip. When dripping, the bridge just gets in the way. Solution? Darn, you guessed it, yep, a bridgeless atomizer aka: debridged or dewicked.
It's like a backseat. If you use it, it's great to have. If you don't need it, it just gets in the way of the rollcage... Well, maybe that's not a great analogy...