CCTV Glossary and Terminology Guide — Complete Dictionary for CCTV Installers
The security industry uses a wide range of technical terms, acronyms, and system-specific language. Whether you are taking a CCTV installation course, working as a technician, or trying to understand how surveillance systems work, this comprehensive CCTV Glossary explains every important term used in HD CCTV, IP CCTV, NVRs, DVRs, and VMS platforms.
This glossary is designed for beginners and professionals alike. It supports your CCTV installation training by giving you clear, practical definitions of the terminology used across the security industry. Terms are organised alphabetically with technical context that explains not just what each term means, but why it matters on a real installation.
A — CCTV Terms
Access Control
A security system that controls entry to buildings or rooms using keypads, cards, biometrics, or mobile credentials. Often integrated with CCTV so that door events trigger camera recording.
AHD (Analog High Definition)
An open-standard HD over coax technology that delivers high-definition video (up to 4K) over coaxial cable. Used in budget-friendly HD CCTV systems alongside HD-TVI and HD-CVI.
AI Detection
Artificial intelligence features in IP cameras that classify objects in the scene — distinguishing between people, vehicles, and other movement. Reduces false alarms compared to basic motion detection.
Analogue CCTV
Legacy CCTV technology using low-resolution (480 TVL) composite video signals over coaxial cable. Largely replaced by HD CCTV and IP CCTV but still encountered on upgrade projects.
Angle of View
The width of the area a camera can see, determined by focal length and sensor size. A wide angle of view (e.g. 2.8mm lens) covers a broad area at short range; a narrow angle of view (e.g. 12mm lens) covers a smaller area at longer range.
ANPR / LPR (Automatic Number Plate Recognition)
A camera and software system that reads vehicle licence plates automatically. Requires specific camera positioning, lens selection, and lighting conditions to work reliably. Also called LPR (License Plate Recognition).
B — CCTV Terms
Bandwidth
The amount of data a network can carry, measured in Mbps or Gbps. Critical for IP CCTV — insufficient bandwidth causes video lag, pixelation, and dropped camera connections. Each IP camera typically uses 2–8 Mbps depending on resolution and compression.
Bitrate
The amount of data used to encode video per second. Higher bitrate produces better image quality but requires more storage and network bandwidth. Measured in Kbps or Mbps.
BNC Connector
A twist-lock connector used for coaxial cables in HD CCTV and analogue systems. Compression BNC connectors are the professional standard; twist-on connectors should be avoided.
Bullet Camera
A cylindrical camera with a visible, directional housing. Common for outdoor perimeter coverage due to its long IR range and visible deterrent effect.
C — CCTV Terms
Cat5e / Cat6 / Cat6A
Categories of Ethernet cable used for IP CCTV. Cat5e supports up to 1 Gbps; Cat6 supports higher bandwidth with lower crosstalk; Cat6A supports 10 Gbps. Cat6 is recommended for new IP CCTV installations because it has lower resistance for PoE delivery.
CCTV (Closed-Circuit Television)
A video surveillance system where cameras send video to a private recording system rather than broadcasting publicly. The term covers all modern surveillance technologies including HD and IP systems.
CGNAT (Carrier-Grade NAT)
A technique used by some ISPs that places multiple customers behind a single public IP address. CGNAT blocks inbound connections, preventing traditional port forwarding for remote CCTV access. The workaround is P2P cloud access or a VPN.
Coaxial Cable
Cable used for analogue and HD CCTV systems. RG59 is the standard for runs up to 200 metres; RG6 supports longer distances. Siamese cable combines coax and power in one jacket.
Compression (Video Compression)
Reduces video file size using codecs like H.264 or H.265. H.265 reduces storage and bandwidth by approximately 50% compared to H.264 at the same quality. Essential for managing storage costs on large systems.
Corridor Mode
A camera orientation that rotates the image to 9:16 (portrait) format, optimised for long narrow spaces such as corridors, aisles, and pathways. Uses more of the sensor area effectively than a standard 16:9 landscape view pointed down a corridor.
D — CCTV Terms
DHCP (Dynamic Host Configuration Protocol)
A network protocol that automatically assigns IP addresses to devices. Not recommended for CCTV cameras because the address can change after a power cycle, causing the NVR to lose the camera. Use static IP addresses for cameras instead.
Dome Camera
A compact, vandal-resistant camera enclosed in a dome housing. Popular for indoor commercial environments because the dome conceals the lens direction. Can suffer from IR reflection off the dome cover at night.
DORI (Detect, Observe, Recognise, Identify)
An industry framework for specifying image quality requirements based on pixels per metre. Detect (25 PPM): something is there. Observe (62 PPM): what are they doing? Recognise (125 PPM): is this someone we know? Identify (250 PPM): evidence-grade for prosecution. Used to specify the right camera and lens for each zone of a site.
DVR (Digital Video Recorder)
A recorder used with analogue and HD CCTV cameras. Receives video over coaxial cable, processes it, and writes it to a hard drive. Channel count is fixed by the hardware (4, 8, 16, or 32 channels).
Dynamic Range (WDR)
See WDR.
Day/Night Camera
A camera with a mechanical IR cut filter that switches between colour mode (day) and infrared mode (night) based on ambient light levels.
E — CCTV Terms
Edge Recording
Recording video directly onto an SD card inside the camera rather than on a central NVR. Used as a backup in case the NVR or network fails, ensuring footage is not lost during outages.
Ethernet
The networking technology used for IP CCTV systems. Carries data and power (via PoE) over Cat5e, Cat6, or Cat6A cable. Maximum cable length per segment is 100 metres.
Exposure
Controls how much light reaches the camera sensor, affecting image brightness and clarity. Most CCTV cameras use automatic exposure; manual adjustment is available for challenging lighting conditions.
F — CCTV Terms
Fisheye Camera
A camera with an ultra-wide-angle lens (typically 180° or 360°) that captures a panoramic view. The distorted image is corrected (dewarped) in software on the NVR or VMS. A single fisheye can replace several standard cameras in some environments.
Focal Length
The distance between the lens and the image sensor, measured in millimetres. A short focal length (2.8mm) gives a wide angle of view; a long focal length (12mm+) gives a narrow, zoomed-in view. Determines what the camera can see and at what distance.
FPS (Frames Per Second)
The number of video frames captured per second. Higher FPS produces smoother video but requires more storage and bandwidth. 15 FPS is common for recording; 25–30 FPS for smooth live viewing.
Fixed Lens
A lens with a set focal length that cannot be adjusted. Simpler and cheaper than varifocal lenses but requires the installer to choose the correct focal length before purchase.
G — CCTV Terms
Gateway
The network device (usually a router) that connects a local network to the internet. Every CCTV device that needs internet access (for remote viewing) must have the correct gateway address configured.
Ground Loop
An electrical interference problem caused when a camera and DVR are powered from different electrical circuits with different earth potentials. Causes rolling bars or horizontal lines across the video image. Fixed with a ground loop isolator or by powering devices from the same electrical source.
H — CCTV Terms
H.264 / H.265 / H.265+
Video compression codecs. H.264 is widely supported. H.265 (HEVC) halves the storage and bandwidth required at the same quality. H.265+ is a proprietary enhancement by some manufacturers that further reduces storage. Use H.265 wherever camera and recorder both support it.
HD CCTV
High-definition CCTV using coaxial cable. Includes HD-TVI, HD-CVI, and AHD technologies supporting resolutions from 1080p to 4K. See our HD CCTV module for full training.
Hybrid DVR/NVR
A recorder that supports both coaxial (HD CCTV) and Ethernet (IP CCTV) camera inputs. Allows gradual migration from HD to IP without replacing the entire system.
I — CCTV Terms
IK Rating
Measures a camera’s resistance to physical impact. IK10 is the highest rating, meaning the camera withstands 20 joules of impact (equivalent to a 5kg mass dropped from 40cm). Important for vandal-prone locations.
IP Address
A unique numerical identifier for every device on a network. IP cameras must have unique static IP addresses to ensure stable NVR connections. Conflicts (two devices with the same IP) cause intermittent faults.
IP Camera
A network-based camera that transmits digital video over Ethernet. Offers higher resolution, on-camera analytics, and PoE power compared to coaxial cameras. See our IP CCTV module for full training.
IP Rating (Ingress Protection)
A two-digit code indicating a camera’s protection against dust and water. IP66 (protected against powerful water jets) is standard for outdoor CCTV. IP67 allows temporary submersion. Always check the IP rating before specifying an outdoor camera.
IR (Infrared)
Invisible light used by cameras to illuminate scenes in darkness. Built-in IR LEDs provide night vision without visible light. 850nm LEDs produce a faint red glow; 940nm LEDs are invisible but have shorter range.
L — CCTV Terms
LAN (Local Area Network)
The internal network connecting IP cameras, switches, NVRs, and VMS servers. CCTV should ideally be on a separate LAN or VLAN from the business network.
Latency
The delay between a live event and its display on screen. High latency makes PTZ control difficult and live monitoring less effective. Caused by network congestion, excessive compression processing, or slow remote connections.
Lux Rating
Measures how well a camera performs in low light. Lower lux = better performance in darkness. A camera rated at 0.01 lux can capture usable colour images in very dim conditions. 0 lux means the camera relies entirely on IR illumination.
From Vocabulary to Real Skills
Knowing the terms is step one — applying them on a live site is step two. The complete CCTV installation course turns this glossary into 22 hours of practical training where every term gets used in a real configuration, real cabling decision, or real troubleshooting scenario.
M — CCTV Terms
Megapixel (MP)
A measure of camera resolution. 2MP = 1080p, 4MP = 2K, 8MP = 4K. Higher megapixel counts provide more detail but require more storage and bandwidth.
Motion Detection
A feature that triggers recording or alerts when pixel changes are detected in defined zones. Modern cameras use AI-based motion detection that distinguishes between people, vehicles, and environmental movement (wind, rain).
Multi-Sensor Camera
A camera housing with multiple lenses (typically 2 or 4) providing wide panoramic coverage from a single mounting point. Reduces the number of cameras needed for large open areas.
N — CCTV Terms
NVR (Network Video Recorder)
A recorder for IP CCTV systems that receives compressed digital video from cameras over the network. Unlike DVRs, NVRs do not process the video — the camera handles encoding. See our System Types guide for DVR vs NVR comparison.
Network Switch
A device that connects multiple IP cameras and network devices. PoE switches provide both data connectivity and electrical power to cameras over a single cable.
Noise
Visual distortion (grain, speckle) in low-light video caused by the sensor amplifying a weak signal. Cameras with larger sensors and better processors produce less noise in low-light conditions.
O — CCTV Terms
ONVIF
An industry standard protocol that allows IP cameras and NVRs from different manufacturers to work together. ONVIF Profile S covers video streaming; Profile G covers recording; Profile T covers advanced streaming features. Always verify ONVIF compatibility when mixing brands.
Outdoor Camera
A camera designed for external environments with weatherproofing (typically IP66 or IP67), UV-resistant housing, and often wider operating temperature ranges. See IP Rating.
P — CCTV Terms
P2P (Peer-to-Peer) Cloud Access
A remote access method where the NVR connects to the manufacturer’s cloud server, and the mobile app connects through the same cloud — bypassing the need for port forwarding. The simplest remote access method for most installations.
PoE (Power over Ethernet)
Technology that delivers electrical power and data to IP cameras through a single Ethernet cable. Standards: 802.3af (15.4W), 802.3at PoE+ (30W), 802.3bt PoE++ (60W/90W). Eliminates separate power cables.
PTZ Camera (Pan-Tilt-Zoom)
A camera that can pan (rotate horizontally), tilt (angle vertically), and zoom remotely. Used for monitoring large open areas. Configured with presets, patrol tours, and sometimes auto-tracking. Requires PoE+ or PoE++ power.
Pixelation
Blocky or distorted video caused by excessive compression, insufficient bitrate, or network packet loss. Fix by increasing bitrate, improving cable quality, or reducing camera resolution.
R — CCTV Terms
RAID
Redundant Array of Independent Disks. A storage configuration that protects against hard drive failure. RAID 1 mirrors two drives. RAID 5 uses three or more drives with distributed parity (survives one drive failure). Used in NVRs and VMS servers where data loss is unacceptable.
Remote Access
Viewing live or recorded CCTV footage from outside the local network — typically via a phone app, web browser, or VMS client. Methods include P2P cloud access and port forwarding.
Resolution
The clarity of video measured in pixels. Common CCTV resolutions: 1080p (2MP), 4MP, 5MP, 4K/8MP. Higher resolution captures more detail but increases storage and bandwidth requirements.
Ring Buffer
The default recording method in CCTV systems. When the hard drive is full, the oldest footage is automatically overwritten by new recordings. Retention period = total storage capacity ÷ daily recording rate.
RTSP (Real Time Streaming Protocol)
A network protocol used to stream video from IP cameras to NVRs, VMS platforms, or third-party software. Each camera provides an RTSP URL that other devices use to access its video stream.
S — CCTV Terms
Smart Events
Advanced analytics beyond basic motion detection, including line crossing, intrusion zone, object removal, loitering detection, and scene change. Configurable on most modern IP cameras.
Static IP
A permanently assigned IP address that does not change. Essential for CCTV cameras and NVRs to ensure stable connections. Contrast with DHCP, which assigns addresses dynamically.
Storage Retention
The number of days of footage stored before the oldest recordings are overwritten. Typical retention: 7–14 days for residential, 30 days for commercial, 90+ days for regulated environments.
Subnet / Subnet Mask
Defines which devices can communicate directly on a network. Cameras and the NVR must be on the same subnet to communicate. The most common subnet mask for CCTV is 255.255.255.0, which allows 254 devices on the same network segment.
T — CCTV Terms
Turret Camera
Also called an eyeball camera. A compact camera without a dome cover, combining the benefits of dome (small size, direction-concealment) and bullet (no IR reflection from dome). The most popular general-purpose camera type for both indoor and outdoor installations.
Thermal Camera
A camera that detects heat signatures (infrared radiation) rather than visible light. Used for perimeter detection in complete darkness, detecting people or vehicles by body heat regardless of lighting conditions. More expensive than standard cameras.
U — CCTV Terms
UPS (Uninterruptible Power Supply)
A battery backup device that keeps the NVR or recording server running during power outages. Also protects equipment from voltage spikes and surges. Recommended for every professional CCTV installation.
V — CCTV Terms
Varifocal Lens
A lens that allows manual or motorised adjustment of focal length, changing the angle of view after installation. Ideal when the exact coverage area is uncertain at the time of purchase.
Video Loss
When a camera signal disappears, showing a black or blue screen on the recorder. Caused by power failure, cable damage, loose connectors, or network issues. See our Troubleshooting Guide for systematic diagnosis.
VLAN (Virtual LAN)
A logical network separation configured on a managed switch. Used to isolate CCTV traffic from business network traffic for security and performance. Standard practice on commercial IP CCTV installations.
VMS (Video Management System)
Enterprise software for managing large CCTV systems across multiple sites. Provides centralised monitoring, user roles, analytics integration, and multi-server recording. See our VMS training module.
W — CCTV Terms
WDR (Wide Dynamic Range)
A camera feature that balances bright and dark areas in the same image. Essential for cameras facing windows, doorways, or other scenes where sunlight and shadow create extreme contrast. Without WDR, either the bright area is overexposed or the dark area is too dark to see.
Wireless CCTV
Cameras that transmit video over Wi-Fi instead of Ethernet cable. Convenient for temporary installations but less reliable than wired systems due to signal interference, bandwidth sharing, and range limitations.
Learn CCTV Terminology Through Professional Training
Understanding CCTV terminology is essential for installers, technicians, and anyone working with surveillance systems. Our complete CCTV installation course covers all of these terms in context, with real-world demonstrations showing how each concept applies on actual installations. You will learn not just what each term means, but when it matters and how it affects the decisions you make on site.
Explore related guides: CCTV System Types Explained, CCTV Troubleshooting Guide, Tools and Equipment Guide, and Security Camera Installation for Beginners.