An analog camera sends video as a continuous signal over coaxial cable to a recorder rather than as packets over a network. It extends easily on existing coax and needs no addressing, but resolution, remote viewing and analytics are limited compared with network cameras, and each camera needs its own cable home.
Analog cameras are still in service in many buildings, and they are not automatically the wrong choice. What matters is whether the wiring already exists and whether the footage has to hold up at a distance.
How the signal travels
The camera outputs a video signal that a recorder digitizes and compresses. Because the link is point to point, every camera runs its own cable back to the recorder, so recorders sit near the cabling. Power arrives separately or over the same coax through a converter.
Where analog still makes sense
A small site with sound coax and a working recorder can add a camera without rebuilding the network. Analog also suits short, simple runs where nothing needs analytics. For a new install with remote access and detail in mind, network cameras are the more capable base.