Downbeating describes the technique whereby natural harmonics are used in tuning guitars. This is a very effective way to tune guitars that can be more accurate than just tuning by ear. It is also a great way of fine tuning once your have approximated tuning with standard techniques.
A prerequisite technique you must learn before you can use downbeating is hitting natural harmonics. Natural harmonics are produced by picking the string while lightly touching the string over the fret wire. You don