Use of generation is often divided into three categories — baseload, which is generation run all 24 hours of the day; intermediate, which is run from mid-morning until the evening; and peaking, which is run during the peak hours (often from late afternoon until early evening).
Baseload generation is typically satisfied by nuclear units, high-efficiency coal and natural gas units, hydro generation, and cogeneration units. In the future baseload may also be provided by offshore wind power.