Major-chord progressions are constructed in the harmonization of major scales in triads.[21] For example, stacking the C-major scale with thirds creates a chord progression, which is traditionally enumerated with the Roman numerals I, ii, iii, IV, V, vi, viio; its sub-progression C-F-G (I-IV-V) is used in popular music,[22] as already discussed. Further chords are constructed by stacking additional thirds. Stacking the dominant major-triad with a minor third creates the dominant seventh chord, which shall be discussed after minor chords.

The original purpose of the resonator was to produce a very loud sound; this purpose has been largely superseded by electrical amplification, but the resonator guitar is still played because of its distinctive tone. Resonator guitars may have either one or three resonator cones. The method of transmitting sound resonance to the cone is either a "biscuit" bridge, made of a small piece of hardwood at the vertex of the cone (Nationals), or a "spider" bridge, made of metal and mounted around the rim of the (inverted) cone (Dobros). Three-cone resonators always use a specialized metal bridge. The type of resonator guitar with a neck with a square cross-section—called "square neck" or "Hawaiian"—is usually played face up, on the lap of the seated player, and often with a metal or glass slide. The round neck resonator guitars are normally played in the same fashion as other guitars, although slides are also often used, especially in blues.
You can tell whether or not strings are of a thin or thick gauge based on the numbers on the package. The smallest number, which is the gauge of thinnest string, will usually be .9 or lower on thin gauge strings. On thick gauge strings this number will be .12 or higher. Strings that are .10 or .11 are generally considered to be “mediums”, and produce a tone and feel which is the middle ground between these two extremes.
In an acoustic instrument, the body of the guitar is a major determinant of the overall sound quality. The guitar top, or soundboard, is a finely crafted and engineered element made of tonewoods such as spruce and red cedar. This thin piece of wood, often only 2 or 3 mm thick, is strengthened by differing types of internal bracing. Many luthiers consider the top the dominant factor in determining the sound quality. The majority of the instrument's sound is heard through the vibration of the guitar top as the energy of the vibrating strings is transferred to it. The body of an acoustic guitar has a sound hole through which sound projects. The sound hole is usually a round hole in the top of the guitar under the strings. Air inside the body vibrates as the guitar top and body is vibrated by the strings, and the response of the air cavity at different frequencies is characterized, like the rest of the guitar body, by a number of resonance modes at which it responds more strongly.
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.