Flyrodders hate knots, and hate them most when they start bumping through guides as a trophy saltwater gamefish takes off on a run. To take some of the bumps out of fly fishing, install a Spliced Loop in Backing Lines and a Braided Monofilament Loop on the end of your fly line.
The Loop-to-Loop Connection is strong, and best of all, much smoother than Nail Knots or any other method of joining a fly line to Backing.
You can make these splices because braided monofilament line is actually hollow. Most backing lines are also "hollow," but there are exceptions, specifically the newer gel-spun lines. It's a totally different manufacturing process and you will not be able to insert a splicing needle into the line. You might also find it difficult to splice backing lines under 30-pound-test. In these cases, you can tie a Bimini Twist loop in the backing.
This method of installing a Spliced Loop in Backing is essential to setting up a Shooting Head system. [There are three images below. Give them time to load.]

Note that Diagram #3 shows an extra "tuck" that's used to make for a firmer loop connection in a backing line. It's not necessary for splicing a loop in a braided monofilament.
Though this is a solid splice, you should cover it and the crotch of the loop with a thin mixture of Aquaseal and its accelerator, Cotol-240. Allow the Aquaseal to cure for about one hour before you connect your fly line, spool your reel, and go fishing.