You use a Palermo Knot. It is easy to tie and works well. Use it mostly for jig fishing because it mends so well and floats. You get immediate action on a pull.

You can use for drift fishing, but don't use it around other people (combat fishing). You will get other people upset if you snag with them. It is very hard to unsnag with others.

Check this web site for knots: http://www.fish4fun.com/palomarknot.htm
Hope this helps.

Steve