The field of continuous electroencephalographic monitoring (cEEG) in the intensive care unit has dramatically expanded over the past two decades. Expansion of cEEG programs led to recognition of the frequent occurrence of electrographic seizures, and complex rhythmic and periodic patterns in various critically ill populations. The majority of electrographic seizures are of nonconvulsive nature, hence the need for cEEG for their identification. Guidelines on when and how to perform cEEG and standardized nomenclature for description of rhythmic and periodic patterns are now available. Quantitative EEG analysis methods depict EEG data in a compressed (hours on one screen) colorful graphical representation, facilitating early identification of key events, recognition of slow, long-term trends, and timely therapeutic intervention. Integration of EEG with other invasive and noninvasive modalities of monitoring brain function provides critical information about the development of secondary neuronal injury, providing a valuable window of opportunity for intervention before irreversible damage ensues.