This chapter reviews the history of glaciation on Earth during the Cenozoic era (the past 65 million years) compiled from ocean sediment cores, notably by a deduction from their oxygen isotope ratio records of global ice volume changes. It examines the character of the ice age cycles during the Pleistocene (the last 2.6 million years), whose recent part of the history is informed additionally by ice core records. The treatment covers external and internal forcing factors of climate variability, including orbital-driven variations of incoming solar radiation (Milankovic cycles) and the feedbacks between cryosphere, climate and the carbon cycle.