Closed circuit television (CCTV) is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors. Most CCTV systems include digital video recorder (DVR) or network video recorder (NVR) to record video for up to more than one month. Some CCTV systems provide remote surveillance functions. The recent high density (HD) technology is also applied to CCTV system to meet some higher requirements. 把攝像機視訊傳送到指定地點供固定數目的監視器，是為閉路電視。多數閉路電視系統包括數碼視像錄影機（DVR）或網路視像錄影機（NVR），可錄影多至超過一個月視像。部份閉路電視系統還提供遙距監察功能。近期的高清電視技術亦有應用於閉路電視系統，滿足一些較高的要求。