Beginners often buy a guitar chord book, and then frown when they see so many chords inside. "So many chords! Is this guitar chord book complete? How many chords are there?"

There are as many chords as you want them to be. Chords are made up of 3 or more notes played together.

Let's take the mother of all scales first, key of C major (2 Octaves), we have:-
C D E F G A B C D E F G A B C
(remember the alphabetical sequence - Learn How To Count)

To build any chord (lets build each chord based on 3-notes pattern first) we just take any note, this will be our 1st note, and build up with its 3rd and 5th notes like this:-

(Start) C(1st) E(3rd) G(5th) - chord name C major - aka Chord I
(Start) D(1st) F(3rd) A(5th) - chord name D minor - aka Chord II
(Start) E G B - chord name E minor - aka Chord III
(Start) F A C - chord name F major - aka Chord IV
(Start) G B D - chord name G major - aka Chord V
(Start) A C E - chord name A minor - aka Chord VI
(Start) B D F - chord name B half diminshed - aka Chord VII

If you can play all the chords above on your guitar, you can play many many songs in the key of Cmajor. Try play this pattern Chord I - VI - II - V || I - VI - II - V || I (end)

But we can also build 4-notes chords, 5-notes or even 6-notes chords with its 7th, 9th,11th and 13th notes.

This is a 4-notes chord built on 1,3,5,7:-

C(1st) E(3rd) G(5th) B(7th) - chord name C major 7

... and like wise we can build chords for each of the other notes above.... and this only the C major scale, there's the C minor (natural, harmonic or melodic) scales... and what about say the Bb (flat) major scale?... where each we can build with 3rd, 5th, 7th, 9th, 11th, 13th notes, sharpen or flatten the 5th, 9th, etc to give more kick!!.... and each has a chord name. So there it goes - there are many many chords.

Don't worry about learning too many chords. You cannot finish anyway. Just learn the basic chords in the key of C, G, D and A and you are good to go on many songs. You will pickup more intricate chords while learning more songs.

The good news is - it is the shape of the chord on your guitar that is more important. Learn one shape, say the shape of the A chord (all 3 fingers in second fret), transpose this shape up the fretboard, and you already know the A# (or Bb) chord, B chord, C, C#, D, D# etc..... You must of course know how to count!