The Bimini twist is not a connection to a hook or a leader, it is a way to create a doubled section of your main line with almost no loss of strength, and a built-in shock-absorbing loop. That double line is the foundation that offshore anglers build their leaders and connections on, the starting point for serious big-game rigs.
When and why to use it
Use a Bimini when you are chasing offshore big game, tuna, marlin, sharks, and need a strong doubled line to build from: to attach a heavy leader or wind-on, to create a class-tippet loop, or to add strength and stretch where a giant will test everything. It is overkill inshore, but essential in the canyons.
How it works
You form a long loop and put a set number of twists in it (often 20+), then, keeping tension, let those twists roll back over themselves before locking the loop off with a series of hitches. The rolled twists distribute the load so the doubled line retains nearly its full strength. It takes two hands (or a helper) and practice to do cleanly.
Tip Practice the Bimini at home until you can do it in your sleep, because you tie it before you leave the dock, not with a fish on. Count your twists consistently and keep even tension as they roll back, that even lay is what preserves the near-full strength.