When you play notes separately, one after another, you are playing a melody. The distance between these notes is called a melodic interval.
A major chord is played using the 1st (root) + 3rd + 5th notes of a major scale.
A minor chord is played using the 1st (root) + 3rd + 5th notes of a minor scale.
The symbol used to signify a major 7th is maj7 while min7 stands for minor 7th.
A dominant 7th uses the symbol of a note name + 7. For example: C7, D7, E7, etc.
Chord inversions are used by composers and musicians for modulation, to create a melodic bass line and generally to make music more interesting.
Sus is an abbreviation for "suspended", it refers to chords that doesn't follow the common triad pattern.
There are other chords, like the 6th and 9th chords, you can use to make your music more interesting.
There are two more types of triads called diminished and augmented chords
Consonant chords sound harmonious and pleasing, while dissonant chords elicit a feeling of tension and sounds like the notes are clashing.