Em chord inversions
Em/G and Em/B are the first and second inversions of the E minor. This means that the bass tone is shifting from E to G or B.
Em/G
Em/B
Try in chord progressions
Am - Em/G - F
Am - Em/B - C
Comments
When stumble upon these chord names, you can choose to ignore the alternate bass note and play the regular E minor. It will always sound ok, but it may lack some subtle additions to the sound. Among the two presented inverted versions above, Em/B is much more common (especially since it often play unintentionally instead of the normal E minor). There are few situations in which Em/G comes handy.
Alternative fingerings
Apart from the diagram version, another option for Em/D is X2X000, which is suitable for some fingerpicking situations.
Theory of the Em/G and Em/B chords
Both chords consist of the notes E, G, B. The difference is that the order of notes shifts. G is the bass note in the first inversion and B is the bass note in the second inversion.
Alternative chord names
Em/G is identical with G6(no5).
See alsoEm7 inversions
Chord construction
Em E - B - E - G - B - E
Em/G G - B - E - G - B - E
Em/B x - B - E - G - B - E
Guitar versions of the chord
Notes in chord
Em E - G - BEm/G G - B - E
Em/B B - E - G
Note structure in theory