The universal capabilities of high resolution spot profile analysis low energy electron diffraction for in situ studies of surface morphology and surface defects will be discussed and demonstrated. The position of the diffraction spots is used to determine lateral lattice constants, step heights and the strain state of heterosystems with a precision of 0.02Å. With the knowledge of the spot profile we could determine island and domain size distributions - even during deposition - and correlation functions of arbitrary surface defects. The variation of the spot profile with electron energy allows the evaluation of the 3dim. reciprocal space. With this the power spectrum of surface roughness, facet orientation, or step morphology of flat and vicinal surfaces could be completely characterised.