Some older analog video surveillance systems feature cameras capable of delivering resolutions that are described by their number of “television lines,” or TVL. TVL refers to the number of broadcast TV lines as viewed on a monitor screen. Generally, the higher the TVL, the greater the resolution of displayed images. These days, consumers are more likely to be familiar with effective pixel densities. For example, a camera that provides 480 TVL features 510 x 492 pixels. In contrast, a camera capable of rendering images with 700 TVL resolution would deliver an image with about 976 x 582 pixels. For comparison, note that a modern higher-resolution camera designated 720p HD provides 1280 x 720 pixels of resolution. An analog or digital camera capable of providing some of the highest resolution available might feature 1080p (or 2.1 MegaPixel (MP)) resolution. This would yield 1920x1080 pixels. This is comparable to the resolution most consumers are accustomed to from viewing HD programming on their home 1080p HD television sets. Cameras with 480 TVL may suffice when precise detail is not essential. You’ll still be able to see a stranger at the door, for instance, with a 480 TVL camera in operation. But you may not be able to see details about the person’s appearance, as you would with a higher-resolution camera.