An analog camera sends an analog video signal over coax cable to a DVR or an encoder, rather than producing a digital network stream. It is the legacy plant that IP cameras largely replaced: simple, cheap, and dependent on a back-end recorder to digitise and store its picture. The camera itself has no IP address, no on-board compression worth the name, and no ability to run analytics.
For decades analog was the default, and a huge installed base still exists. "HD-over-coax" standards (HD-TVI, HD-CVI, AHD) modernised it by carrying megapixel resolution over the same coax to a compatible recorder, so an existing analog run can be upgraded in image quality without pulling new cable. An encoder (video server) is the other bridge: it digitises analog cameras onto an IP network so a VMS can record them alongside IP cameras.
The limits are why new systems rarely start here: lower resolution than modern IP cameras, one home-run cable per camera, no edge intelligence, and a separate power supply at each camera. Analog makes sense to preserve an existing investment; for a green-field deployment, IP cameras with PoE and a VMS are the stronger foundation.
