Visual displays of quantitative EEG, consisting of mathematical processing of EEG signals for graphical display, are powerful tools to enhance review of raw EEG. Quantitative EEG is widely used for seizure detection and for delayed cerebral ischemia detection, and it improves efficiency of long-term monitoring review. Here, we review the signature "footprints" of periodic and rhythmic patterns on quantitative EEG. While changes in the frequency and rhythmicity shown on quantitative EEG can highlight these patterns, review of raw EEG to evaluate and confirm the pattern is vital.