The secondary camera on a modern smart phone is often known as the front facing camera or 'selfie' cam.
The technologies detailed in the primary camera definition also apply to the secondary camera.
The front facing camera is most commonly used for capturing self portraits/group shots for Social Media and video calling.
Additionally, the front facing cameras work in conjunction with supplemental technology to provide face-detection for smart phone security.
Android has had the ability to unlock your phone via rudimentary facial Recognition called Face Unlock since Version 4.0, Ice Cream Sandwich was unveiled on October 19, 2011. This has never been advertised as secure though.
In Sept 2017, the Samsung Galaxy Note 7 was the first Samsung phone to introduce iris scanning to provide a secure method of unlocking a phone.
In Sept '17, Apple announced the iPhone X that replaced Touch ID, Apple's fingerprint bio-metric security, with Face ID.
FaceID is made even more robust as 'depth' can also be sensed by using the camera in conjunction with the new technology. A byproduct of this is that Apple are one of the first manufactures to introduce 3D Avatars or Animoji capturing a users voice and expressions.
A-GPS (Assisted GPS) | A2DP (Advanced Audio Distribution Profile) | AAC (Advanced Audio Coding) | Accelerometer | Airplane mode | Alarm Clock | Alphanumeric | AMOLED display (Active-matrix organic light-emitting diode) | Analog | Android | ANT+ | Antenna | APN (Access Point Name) | Apple AirPlay | Apple AirPlay 2 | Apple iOS | Apple iOS 10 | Apple iOS 11 | Apple iOS 12 | Apple iOS 7 | Apple iOS 8 | Apple iOS 9 | Apple Pay | aptX | Audio jack | Auto-focus | AVRCP (Audio/Video Remote Control Profile)
Bada OS | Band | Bandwidth | Bar | Base Station | BeiDou Navigation Satellite System | Benchmarking | Biometrics | Bit | BlackBerry OS | BlackBerry Playbook OS | Bluetooth | bps (Bits per Second) | Brand | Broadband | Browser | Byte
Calculator | Calendar | Call alerts | Calling Plan | Camera | Capacitive Touchscreen | Car Kit | Carrier | CDMA (Code-Division Multiple Access) | CDMA2000 | Cell | Chipset | cHTML (Compact HyperText Markup Language) | CIF (Common Intermediate Format) | Clamshell | CMOS (Complementary metal-oxidesemiconductor) | Color depth | Concatenated SMS | Connected GPS | Construction | Corning Gorilla Glass | CPU (Central Processing Unit) | Crosstalk | CSTN (Color Super Twisted Nematic) | CTIA | Custom ringtones | CyanogenMod
D-Pad (Direction Pad) | Data Disclaimer | DC-HSDPA (Dual Carrier or Dual Cell High-Speed Downlink Packet Access) | Digital Zoom | Display type | DLNA (Digital Living Network Alliance) | DNSe (Digital Natural Sound engine) | Downlink | DRM (Digital Rights Management) | Dual-band | Dual-Mode | Dual-SIM | DVB-H (Digital Video Broadcasting - Handheld) | Dynamic Memory
EDGE (Enhanced Data for Global Evolution) | EDR (Enhanced Data Rate) | EGPRS | EGSM (Extended GSM) | Email client | Emoji | EMS (Enhanced Message Service) | eSIM | EV-DO | EV-DV | Exchangeable covers | External Antenna Jack | External Display
FCC (Federal Communications Commission) | Feature Phone | Femtocell | Firefox OS | Firmware | Fixed-focus | Flash Memory | Flight mode | Flip-down phone | FM Radio | FM Transmitter | Form factor | FOTA (Firmware Over-The-Air) | FPS (Frames Per Second) | Frame Error Rate | Frequency | FTP (File Transfer Protocol)
Galileo (Global Navigation Satellite System) | GB (Gigabyte) | Gbps (Gigabits per second) | Geo-tag | GLONASS (Global Navigation Satellite System) | GPRS | GPS (Global Positioning System) | gpsONE | gpsOneXTRA Assistance technology | GPU (Graphics Processing Unit)
H.263 | H.264 | H.265 | Half-QWERTY keyboard layout | Handwriting recognition | Haptics | HEVC | Hot Spot | Hot Swap | HSCSD (High-Speed Circuit Switched Data) | HSDPA (High-Speed Downlink Packet Access) | HSDPA+ (High-Speed Downlink Packet Access Plus) | HSP (Headset Profile) | HSUPA (High-Speed Uplink Packet Access) | HTML (Hypertext Markup Language) | Hz (Hertz)
iDEN (Integrated Digital Enhanced Network) | IMAP (Internet Message Access Protocol) | IMEI (International Mobile Equipment Identity) | IP (Internet Protocol) | IP Ratings | IrDA (Infrared Data Association)
Land line | LCD (Liquid Crystal Display) | LED (Light-Emitting Diode) | Li-Ion (Lithium Ion) | Li-Polymer (Lithium Polymer) | LiMo OS | Linux | Location-Based Services (LBS) | Lock code | Long SMS | Long Term Evolution (LTE) | Loudspeaker
Macro | Maemo OS | Magnetometer | mAh | Mass Storage mode | MB (Megabyte) | Mbps (Megabit per second) | MeeGo OS | Megapixel | Memory card slot | Memory effect | Messaging | MHz (Megahertz) | Micro USB | microSD | microSDHC | Microsoft Exchange (Server) | MIDI (Musical Instrument Digital Interface) | MIDP (Mobile Information Device Profile) | Mil-Spec (MIL-STD) | MIMO | Mini-USB | miniSD | MMC | MMCmobile | MMS (Multimedia Messaging Service) | Mobile games | Mobile High-Definition Link (MHL) | Mobile IM (Instant Messaging) | Mobile WiMAX | Mobility DisplayPort (MyDP) | Modem | Monochrome | MP3 (MPEG Layer 3) | MPEG (Motion Picture Experts Group) | MPEG-4 video | Multitouch input method | Music playback time (battery life) | Music Player
Packet Data | Pager | PC Sync | PCS (Personal Communications Service) | PDA (Personal Digital Assistant) | Percentile rank | Phone Book Access (PBA) | Phone Life Cycle | Phone Physical Attributes | Phonebook | PIM (Personal Information Manager/Management) | PIN code (Personal Identification Number) | Pixel | Pixel density (Pixels Per Inch) | Polyphonic ringtones | POP3 (Post Office Protocol) | Port | Predictive text input | Price | PTT (Push-To-Talk) | PUK Code (PIN UnlocK Code) | Push
RAM (Random-Access Memory) | RBDS (Radio Broadcast Data System) | RDS (Radio Data System) | Resistive touchscreen | Resolution | Ringer ID | Ringing profiles | Ringtone | Roaming | ROM (Read-Only Memory) | RS-MMC (Reduced-Size Multi Media Card) | RSA (Rural Service Area) | RSS (Rich Site Summary) | Ruggedized (Rugged)
S60 user interface | SAP (SIM Access Profile) | SAR (Specific absorption rate) | Screen protection | SD (Secure Digital) | Secondary camera | Sensors | Side Keys | SIM | SIM lock | Single-Band | Skin | Slimport | Smart Watch | Smartphone | SMIL | SMS (Short Messaging Service) | SNS (Social network service) | Soft keys | Soft Reset | Speed Dial | Stand-by time (battery life) | Stereo Speakers | Streaming Video | Stylus | Sub-QCIF | SVGA | Symbian | SyncML
Talk time (battery life) | TCP/IP | TD-SCDMA (Time Division-Synchronous Code Division Multiple Access) | TEST | Tethering | Text messaging (texting) | TFD (Thin Film Diode) | TFT (Thin Film Transistor) | Theme | To-Do list | Touchscreen | Trackball | Transflash | Transflective | Tri-band
WAP (Wireless Application protocol) | watchOS | WCDMA(Wideband Code Division Multiple Access) | Wear OS | Wearable Technology | webOS | Wi-Fi | Windows Mobile | Windows Phone OS | Wireless email | WLAN | WMV (Windows Media Video)