How to Tune to a drop D tuning on an electric guitar

This video describes the process of tuning the E string on a guitar down to D. The presenter explains this is a great effect for heavy metal and hard rock and makes playing power chords much easier. The method is to listen to the open D string on the guitar and then tune the E string to the same pitch. Since this is the thicker string it will sound one octave lower than the open D string. After the tuning is complete the presenter demonstrates several power chords and how they are much easier to play with drop D tuning.