There isn't a standard in chord naming. Often, we find many different names for the same chord, specially in the Internet. For this reason, it's important to understand the meaning of the chord names.
A chord name is composed of 4 items:
3) Intervals and/or Dissonances
The fundamental is the main note of the chord.
The mode complements the fundamental, indicating the other notes in the chord. There are 4 main modes:
The chart below shows the notes that belongs to each chord in each mode, as well as its spelling (always using "C" as the fundamental).
Note: ∑ Major chords donít present any extension. For instance, a "F" chord denotes a "F major".
Mode Chord Name Samples Notes
Major C C, E, G
Minor Cm, or Cmin C, Eb, G
Diminished Cļ, or Cdim C, Eb, G, A
Dominant C7 C, E, G, Bb
∑ The fifth usually belongs to the chord.
3) Intervals and/or Dissonances:
Chords are defined as sets of notes. In order to understand their spelling, you must learn about intervals. A musical interval is the number of semitones (or frets, in the guitar) between two notes.
The intervals that don't belong to the basic chord are called "dissonances". These dissonances can be used to complement the chord name.
The possible names for these intervals and/or dissonances, as well as the respective notes, for each fundamental are given in the Word Document attached below.
Note: ∑ Suspended ("sus") chords, as Csus4 and Dsus4/7, exchanges the third note for the fourth note of the scale of the fundamental.
∑ Diminished ("dim") chords are composed by the fundamental, the third, the fifth and the diminished seventh.
Chord names may include a slash ("/"). This slash indicates the bass note (the note after the slash is not the fundamental).
For instance: C/G indicates a "C major", but with "G" as bass.
Dbmaj7 Db, F, Ab, C
A#min6/C# C#, A#, F, G
E4/7 E, A, B, D
G7M(9) G, A, B, D, F#
The above lesson is based on an article from Daccord Guitar Dictionary