Sharp waves and ripples (SWRs) are oscillatory patterns in the mammalian brain hippocampus seen on an EEG during immobility and sleep. There are three major network oscillation patterns in the hippocampus: theta waves, SWRs and gamma waves. Gamma oscillations are found in all major brain structures, whereas theta and sharp waves are specific to the hippocampus and its neighbouring areas. SWRs are composed of large amplitude sharp waves in local field potential and associated fast field oscillations known as ripples. SWRs are shown to be involved in memory consolidation and the replay of wakefulness-acquired memory. These network oscillations are the most synchronous patterns in the brain, making them susceptible to pathological patterns such as epilepsy.