1. Output
1.1. Type of output
1.1.1. Text
1.1.2. Graphics
1.1.3. Audio & video
1.2. Output devices
1.2.1. Monitors -Clarity -Resolution/pixels -Dot pitch -Contrast ratios -Size -Aspect ratio
1.2.1.1. Flat-panel
1.2.1.1.1. LCD
1.2.1.1.2. LED
1.2.1.1.3. OLED
1.2.1.2. Curved
1.2.1.3. E-book readers
1.2.1.3.1. Kindle
1.2.1.3.2. Nook
1.2.1.4. Digital/interactive whiteboards
1.2.1.5. UHDTV
1.2.1.6. Digital projector
1.2.2. Printers -Resolution -Colour -Speed -Memory -Duplex printing
1.2.2.1. Ink-jet
1.2.2.2. Laser
1.2.2.3. 3D
1.2.2.4. Cloud
1.2.2.4.1. Google cloud print
1.2.2.5. Thermal
1.2.2.6. Plotters
1.2.3. Audio-output devices
1.2.3.1. Speakers
1.2.3.2. Headphones
2. Combination of Input and Output devices
2.1. Headsets
2.2. Multifunctional devices (MFD)
2.3. Telephones
2.4. Drones and Robots
2.4.1. Unarmed aerial vehicle
2.4.2. Robots
2.4.3. Virtual reality (VR)
3. Ergonomics
3.1. Study of human factors related to things people use.
4. Input devices
4.1. Keyboard
4.1.1. Traditional
4.1.2. Laptop
4.1.3. Virtual
4.1.4. Thumb
4.2. Mice
4.2.1. Optical
4.2.2. Wireless
4.2.3. Touch pads
4.3. Pointing
4.3.1. Touch screen
4.3.2. Stylus
4.3.3. Game controllers
4.3.3.1. Joystick
4.3.3.2. Gamepad
4.4. Scanning
4.4.1. Optical scanner
4.4.1.1. Document scanner
4.4.1.2. Portable scanner
4.4.2. Card readers
4.4.2.1. Magnetic
4.4.2.1.1. Credit cards
4.4.2.1.2. Entertainment cards
4.4.3. Bar code readers
4.4.3.1. Wand readers
4.4.3.2. UPC
4.4.3.3. MaxiCode
4.4.4. RFID readers
4.4.4.1. tags
4.4.5. Character and mark recognition readers
4.4.5.1. MICR
4.4.5.2. OCR
4.4.5.3. OMR
4.4.6. NFC readers
4.4.6.1. Google Wallet
4.4.7. NFC tags
4.5. Image capturing
4.5.1. Digital camera
4.5.2. Web cams
4.6. Audio input
4.6.1. Voice recognition system
4.6.1.1. Siri
4.6.1.2. Cortana
4.6.1.3. Google Now
4.7. Biometrics Authenticates devices
4.7.1. QR code
4.7.2. Fingerprint reader