Artifacts are noncerebral waveforms that may mimic or obscure cerebral activity. External (nonphysiologic artifacts) are produced outside the body whereas internal (physiologic artifacts) are produced by body organs other than the brain. Electrode artifact may have a spiky, periodic, or rhythmic appearance. Characteristically, it is limited to the involved electrode with no field. Sweat artifact may involve multiple. Eye movement and glossopharyngeal artifact may mimic frontal rhythms. EKG artifact (corresponding with QRS complexes) may be confused with periodic discharges. Ventilatory artifact may be confused with bursts of cerebral activity. Characteristically, it corresponds to the respiratory rate. Head tremor presents as occipital predominant rhythmic artifact. Maneuvers and devices such as bed-percussion, continuous renal replacement therapy, and extracorporeal membrane oxygenation, CPR, and even brushing teeth may lead to ictal appearing rhythmic artifacts. Discharges associated with cortical myoclonus are best appreciated in the central channels as these are relatively free of muscle artifact. Chewing artifact may electrographically mimic a generalized tonic clonic seizure. Close observation of the patient and the surrounding equipment either in person or on video is the key to diagnosing the cause of an artifact and avoid misdiagnosing it as cerebral activity. [191 words/1168 characters]