• AccurateRip
• Acoustid
• AES/EBU
• AirPlay
• Amplifier
• aptX
• Audio file formats
• • AAC
  • AIFF
  • ALAC
  • APE
  • DSD
  • DXD
  • FLAC
  • MP3
  • MQA
  • M4A
  • WAV
  • WMAL
• ASRC
• AVB
• Bit perfect jitter
• Bits: 16 or 24
• Bit perfect playback
• Bitrate
• Bluetooth
• Burn-in
• BWF
• Cables
  • Analog
  • Speaker
  • Bi-wiring
  • Digital
• CDtext
• Chromecast
• Clipping
• Clock
• Codec
• Compression
• CRC
• Crossover
• Cue sheet
• DAC
• Damping
• DASH
• Digital
• Digital Room Correction
• Dither
• DLNA
• Drivers
  • ASIO
  • Direct Sound
  • Kernel Streaming
  • WASAPI
  • Wave Out
• DoP
• DSP
• EBU R128 (loudness)
• FFT
• FireWire
• Freedb
• Gapless playback
• Generation loss
• HDMI
• Headphone listening
• Hearing
  • Single-sided deafness
  • Hard of hearing
• Hires recording
• Homeplug
• I2S
• ID3
• Inter sample peak
• LDAC
• Linearity (DAC)
• Memory playback
• Music Server
• OCF
• OFC
• PCM
• Perception
• RAID
• ReplayGain
• Ripping
• RFI
• RIAA
• Router
• Sampling, up and over
• Sample Rate Conversion
• Speakers
  • Driver design
  • Crossover
  • Amplification
  • Connecting
  • Measurement
  • Placement
• S/PDIF
• Storage
• Sync
• Tagging
• Toslink
• Transcoding
• UAA
• Units
• UPnP
• USB
• VST
• WiFi
• WiSA

Bluetooth is a protocol allowing low power devices to communicate wireless.
A smartphone with a Bluetooth headphone is a popular combination.
Wireless keyboard and mouse often use Bluetooth.
As it is intended to be used with low power devices, its range is limited.

Bluetooth for audio is covered in more detail here.