Backlash, aka, the Birds Nest, is when you don't stop the spool on a bait casting reel when your lure hits the water, or a tree limb etc. they can get ugly.
On a spinning reel, you can run into similar problems that are caused by line twist. This can be prevented with a swivel attached to your line.
On a spinning reel, you can run into similar problems that are caused by line twist. This can be prevented with a swivel attached to your line.