WHAT DOES A LSD DO
As you corner the outside wheel has to cover more distance than the inside one so the diff puts more power to the outside wheel speeding it up.
This has the side-effect though that with a standard diff, as one of the wheels starts to spin the diff supplies more power to the wheel, as it thinks the wheel is going faster because of a corner. A limited slip diff does not do this, it tries to distribute the power more evenly to both wheels.
You still need some differential effect though, or your car would always want to go straight ahead, even when you want to go round corners.