I was walking through a parking lot on the Royal River in Maine. An angler yelled Hey Rod, you changed my life. You taught me the nailless nail knot!
There are various ways of connecting the fly line to the leader. Connector loops, Connector buttons, Connector nails and others.
I find none of them acceptable.
A nail knot is my favorite approach to the transition of line to leader.
As the name implies the Nailless Nail Knot requires no nail and is easy to tie in the field.
I learned this knot from Gary Borger, so why not learn from the best. Go to Gary's web site.
I like to finish as described on the Douple Knot page.