High-resolution EEG recording has become standard in many experimental studies on human brain function and has found its place in the routine presurgical workup of patients with focal epilepsy in several clinical centers. The main aim of high-resolution EEG is source localization with methods that have become increasingly robust and precise. However, high-resolution EEG also allows a spatial analysis of EEG and evoked potentials on the scalp level, thereby identifying topographic features of the scalp potential field. Their value in understanding the dynamics of large-scale networks of the human brain and as markers for neuropsychiatric diseases has been increasingly demonstrated. This chapter discusses the advantages and limitations of such spatial analysis methods and the information that can be gained from them. It also shows that the spatial frequency of the scalp potential field is higher than previously assumed and discusses the consequences regarding the number of channels required to properly capture these spatial frequencies.