There are lots of different types or categories of chords. You don't need to learn all of them, but by learning different types of chords your guitar playing will expand.
The types of chords covered:
Minor add chords are included in the Add9 chords guide. This section was earlier found on this page.
Numeric figures in chord names
As you may notice, there is a lot of numbers involved. In general, these numbers refer to the interval between the root note and the last note in the chord. For example, C7 has the root note c and also e, g and finally b flat which is seventh steps above the root. The b flat note is what separates the C7 chord from a regular C chord.
2: When this number is written out it refers to a sus2 or add2 chord. In these cases the number doesn't refer to the last note in the chord, instead to a note that is replacing another or an added note.
3: This number doesn't occur in chord names, but the third as a musical interval is often part the chords as the second note.
4: This number is mentioned in case of sus4 chords.
5: This number are mentioned concerning the chords that are often called power chords. A fifth as a musical interval is often the last note in triad, but is written out in power chords to indicate that the third is missing and the chord only consists of the root and a fifth.
6: This number indicates that a musical interval in the form of a major or minor sixth is the last note of the chord.
7: A common number in chords and involves major, minor and dominant chords.
8: An eight would refer to a chord with a note one octave up, but it would mean a duplicated note therefore this number doesn't occur in chord names. Especially since it would duplicate the root of the chord, it would be very strange to call a chord something like C8 or Cadd8.
9: Referring to an added nine.
10: This number doesn't occur since it would mean a duplicated third an octave higher.
11: Refer to an expanded chord with an eleventh note added to a dominant seventh.
12: An twelfth whould refered to the fifth one octave up and therefore a duplicated note. This is the reason this number doesn't occur in chord names. Hypothetically, you could call a chord something like C12 or Cadd12, which would imply the notes C, E, G (the G on the next octave).
13: Refers to an expanded chord with a thirteenth note added to a dominant eleventh.
14-: No chords are using numbers higher than thirteen.
Symbols in chord names
Symbols are sometimes used together with or instead of abbreviations.
#: meaning that the note is raised one semi-step (sharp symbol). For exempel Em7#5 includes a raised fifth (E, G, C, D).
b: meaning that the note is lowered one semi-step (flat symbol). For exempel Em7b5 includes a lowered fifth (E, G, Bb, D).
+: a plus sign can stand for augmented or indicates that a note is lowered. For exempel C+ standing for Caug. Or Em7+5 can stand for for Em7 with a raised fifth, the plus sign has the same meaning as the # (sharp symbol).
-: a minus sign indicates that a note is lowered. For exempel Em7-5 includes a lowered fifth, the minus sign has the same meaning as the b (flat symbol).
ø: diminished (letter o with stroke).
°: augmented (a degree symbol, not a zero).
△: major seventh (a delta symbol).
2 note chords, 3 note chords, 4 note chords and others
A chord can consist of two notes (which is unusual and mainly the case when power chords are involved) and more all the way up to seven. The three note chords (also called triads) are the most common and includes major and minor chords. The major 7th and minor 7th are examples of four note chords. Extended chords, like 9th, 11th and 13th, have even more notes in them.
So how to play a seven note chord and a six-stringed instrument? One or more tones are left out, which can be done without the sound or color of the chord is lost.
Chord types and music styles relationship
Yes and no. Certain chord groups can be typical or overrepresented in certain styles, but it's far from a rule.
Anyway, are you interested to learn a specific style, here are some guidelines. As mentioned, this is no strict relationship between groups of chord and music styles, but as a generalization the information below could be good to know.
Blues: dominant sevenths (7th chords)
Jazz: many different types including 11th and 13th chords.
Funk: ninth chords (9th chord)
Punk: power chords (5th chords)
Bossa nova: 6/9 chords
Besides, for rock guitar playing one thing to look into is barre chords and in the singer-songwriter area open chords are fundamental (in both these cases, it's rather concepts or techniques and not groups of chords).
List of chord categories
Here is a list with all sorts of chord categories.
Other major chords
Major 2 (same as add2)
Italian sixth (augmented sixth with three notes: b6 - 1 - #4)
German sixth (augmented sixth with four notes: b6 - 1 - 2 - #4)
French sixth (augmented sixth with four notes: b6 - 1 - 3b - #4)