As previously stated, a dominant seventh is a four-note chord combining a major chord and a minor seventh. For example, the C7 dominant seventh chord adds B♭ to the C-major chord (C,E,G). The naive chord (C,E,G,B♭) spans six frets from fret 3 to fret 8; such seventh chords "contain some pretty serious stretches in the left hand". An illustration shows a naive C7 chord, which would be extremely difficult to play, besides the open-position C7 chord that is conventional in standard tuning. The standard-tuning implementation of a C7 chord is a second-inversion C7 drop 2 chord, in which the second-highest note in a second inversion of the C7 chord is lowered by an octave. Drop-two chords are used for sevenths chords besides the major-minor seventh with dominant function, which are discussed in the section on intermediate chords, below. Drop-two chords are used particularly in jazz guitar. Drop-two second-inversions are examples of openly voiced chords, which are typical of standard tuning and other popular guitar-tunings.
The standard guitar has six strings, but four-, seven-, eight-, nine-, ten-, eleven-, twelve-, thirteen- and eighteen-string guitars are also available. Classical and flamenco guitars historically used gut strings, but these have been superseded by polymer materials, such as nylon and fluorocarbon. Modern guitar strings are constructed from metal, polymers, or animal or plant product materials. Instruments utilizing "steel" strings may have strings made from alloys incorporating steel, nickel or phosphor bronze. Bass strings for both instruments are wound rather than monofilament.
In 1977, the Guitar Institute of Technology (GIT) revolutionized contemporary music education with the first full-time program to offer hands-on professional training for the electric guitarist. Over three decades later, MI remains the leader in guitar education, besting other colleges for guitar players, with a unique system that combines technical, creative and professional development in a performance-based program.