Root on A string
x7878x
Em7♭5 is the E half-diminished chord. Its notes are E, G, B♭ and D. Also written ø7. Often the ii chord in a minor ii–V–i progression.
x7878x
Numbers show frets from the low E string to the high e string; x means don't play that string.
Em7♭5 is the viiø7 chord in F major. That makes it a natural fit in songs written in those keys.
Every E, G, B♭ and D on the first 12 frets. The filled dots are the root, E. Build your own shape from any nearby group.
Other E chords
Other half-diminished chords