Improved Clinch Knot
This is one of the most widely-used fishing knots. It is a requirement of the Fishing and Fly Fishing merit badges. This is best for monofilament line under 30 lb. test. If you are using braided line or heavier than 30 lb. test line, go with the Palomar Knot instead.
To tie the Improved Clinch Knot, first pass your line thru the eye of the hook. Then twist the working end around the main line 5-7 times. Pass the line back thru the first loop formed after the eye, and then through the big loop. Wet the line with saliva to lubricate, then pull on the tag end to tighten down the coils. Clip the tag end close.