The Albright Knot
The Albright knot is used to connect two lines that differ greatly in diameter (say, adding a heavy shock leader to light spinning line). This version includes a lock option to keep the knot from coming undone.
Step 1 Double 3 inches of the heavier line, then pass 8 inches of the lighter line up through the loop.
Step 2 Using the tag end of the light line, make 10 to 12 wraps forward toward the end of the heavy-line loop. Pass the tag end of the light line back down through the loop.
Step 3 Carefully and gently pull on both doubled lines to snug the wraps up against the very end of the heavy-line loop. Now, tighten harder by pulling first on the doubled lines, then on the standing portions of both lines.
Step 4 To lock, use the light-line tag end to make three wraps around the light-line standing portion, wrapping back toward the knot under the created loop. Gently pull the tag end to snug those wraps against the end of the Albright. Pull harder to tighten, then trim. Now your Albright is secure.