A major chord is composed using a root/1st, major 3rd and perfect 5th (or R/1-3-5) intervals played simultaneously. Generally written as the root note (for instance: "C" for a C major chord) it is sometimes written with various additions like Cma or CMA, however it is good practice to use the root note to represent it in writing ie. C
In guitar, the intervals of a major chord may not always be played in tonal order (root/1st, major 3rd, perfect 5th, in this order) however the root note will always be the lowest tone (and most distinct) unless it is an inversion. For example: a C major chord played on the 8th fret using voicing #4 (barre chord) has a interval sequence of: root/1st, perfect 5th, root 1st(octave), major 3rd, perfect 5th and root/1st(x2 octave) or R/1-5-1-3-5-1.
The tonality of a major chord is consonant and resolved, in other words it does not "lead away" from itself like the dominant seventh chord, or leave the listener with a sense of "suspense" like the minor seventh flat five chord.
Major chord profile
|Intervals||root/1st, major 3rd, perfect 5th or R/1-3-5|
|Common names (examples in C)||C, Cmaj, Cma, CMAJ, CMA, CΔ|
Major chord table
|Chord name||Root||Major third||Perfect fifth|
|A♯||A♯||C (D)||E♯ (F)|
|Major chord voicing #1|