A security camera was a type of camera used for surveillance. They were operated to maintain a safe environment in places where unsupervised activity could prove harmful if left unchecked.
The Master used a security camera on a stolen Earth prison transport to observe the Third Doctor and Jo Grant. Jo blocked the camera and began a mundane conversation with herself to bore the Master into turning his attention away from the screen, when the Doctor was busy breaking out. (TV: Frontier in Space)
Security cameras were in use at Global Chemicals. The Third Doctor caught their attention when he tripped a ground sensor while sneaking inside. BOSS and Stevens monitored the Doctor and sent security guards after him, which he subdued. The cameras caught him again when Mike Yates sprung him from a holding cell in the facility after BOSS let Stevens take him prisoner. (TV: The Green Death)
Some types of security cameras were not stationary. By the 51st century, security cameras could act as observation drones. One type of mobile security camera was a hovering, wood covered, mechanical sphere that CAL used to observe the Library when she closed her eyes in her imaginary world. The Tenth Doctor called it "an alive one" after he forced it to reactivate with the sonic screwdriver and CAL reacted with pain. Whatever she said was shown scrolling across a small monitor on the sphere, causing the Doctor to put it down and apologise. A courtesy node later repeated the warning, "Others are coming". (TV: Silence in the Library)