sus4 - A sus4 chord replaces the 1+3+5 pattern with 1+4+5, meaning the third note is replaced by the fourth. For example the tab says you need to play a Dsus4 chord, instead of playing D+F#+A (=1+3+5) you raise the middle note or the third note by a half step. So a Dsus4 chord is D+G+A (=1+4+5). Here are some commonly used sus4 chords for guitar.
sus2 - The sus2 chord follows the pattern 1 (root) + 2 + 5, so if in a sus4 chord you play the root, fourth and fifth notes, for a sus2 chord you play the root, second anf fifth notes. In other words from a sus4 chord you lower the middle note three half steps. For example a Dsus2 chord is D+E+A. Here are some commonly used sus2 chords for guitar.
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