The Gibson Learn & Master Guitar app (free, link) is a guitarist’s Swiss army knife. And it’s as free as a bird now. The app has 4 features that should come in hand to all guitarists, a tuner, a metronome, chord book, and lesson videos.

The chromatic tuner uses the iPhone’s microphone and can tune any instrument. It also has settings for alternate guitar tunings as well. The app can play tones so that you can tune by ear.

For the rhythmically challenged, the app comes with a metronome that beats out the time along with a lever for adjusting BPM (beats per minute). There are settings for multiple time signatures as well—the standard 4/4 as well as 2/3, 3/4, and none). The coolest feature is the ability to tap out your own tempo. Simply hit the Tap Tempo button several times at the speed you want, then app will compute the tempo after a few seconds.

Also featured is a basic chord book that shows you how to place your fingers to form chords as well as high-quality videos of various guitar lessons (Internet connection required).

Gibson Learn & Master Guitar is a free download from the iTunes App Store.