A chord is a selection of note played simultaneously, usually played in ascending order, on the guitar we string the strings together and it gives us a more full sound than playing single notes. There are various types of chords with many different colours which evoke many different responses from us.
On the guitar you can play a chord two different ways, these are 'open' meaning that they include one or more open strings, and 'barred' which usually means that you can slide the chord shape up and down the neck and you will usually bar your finger across multiple strings. Below is an overview of the common types of chord that you will come across in most forms of music. Master these basic shapes and you'll be able to learn most songs you come across accurately.
You get a major chord when we use the root, 3rd and 5th notes of the major scale. If we start on C and count up this would give us the notes 'C', 'E' and 'G', this is the C Major Chord. You can also add in more of those notes to create a fuller sound, this is how most chords are created. Below are the common open major chords that you should practice solidly until they are second nature, they will be valuable all throughout your guitar journey.
There is one change between a major and a minor chord. This is the '3rd', if you lower the it down 1 semi-tone (or 1 fret) then you get the minor version of the chord. For example if you play the C Major Chord which contains 'C', 'E' and 'G', but change the E to an Eb by lowering it by 1 semitone then that will be the C minor chord. Below are the common open minor chords.
DOMINANT 7th CHORDS
The 7th chord, also known as 'dominant 7th' is an extension of the major triad but can be used in a minor or a major context, the notes full names are 'root, major third, perfect fifth, minor seventh'. This type of chord is very common among almost all types of music, it is used as the base chord for most blues music, because of its more colourful sound in comparison to a straight major or minor chord. Below are the common open minor chords.
MAJOR 7th CHORDS
Known for its dreamy, jazzy sound the major 7 chord is created by taking a major triad (root, major third, perfect fifth) and by adding a major 7th. In the key of C Major this would give us four notes consisting of C, E, G, B. As mentioned above major 7th chords are prominent in jazz as well as well as soul, funk, disco, country, rock and many other styles of music.
MINOR 7th CHORDS
Much like the major 7th, it's minor counterpart has an equally colourful, jazzy tonality but being a minor chord it can sound a little more sad and moody. To create a minor 7th chord you take a regular minor triad (route, minor third, perfect fifth) and add a minor 7th. If we wanted to play an a minor 7th chord we would take these notes: A, C, E, G. On the guitar we might not play these notes in order but this is what the chord is made up of. Below is my list of all of the open chords you'll need. Learn these off by heart and you'll be able to learn the chords for most songs, for the ones that are missing, you'll likely need bar chords, but most can be done using open shapes.