The ways wireless Bluetooth transmission can be used are defined in "profile" specifications, and the major profiles are summarized below. See Bluetooth
GAP - Generic Access Profile
SDAP - Service Discovery Application Profile
Device and service discovery.
HSP - Headset Profile
The common headset application, first deployed in 1998.
HFP - Handsfree Profile
Hands-free calling while driving. Headsets use this profile for redial and call waiting. First deployed in 2002.
A2DP - Advanced Audio Distribution Profile
Supports mono and stereo audio. For example, a smartphone transmits MP3 music via A2DP and phone calls via HSP or HFP (see above). See Bluetooth audio
PBAP - Phone Book Access Profile
Transfer a cellphone's contact list to a car's hands-free system.
HID - Human Interface Device
Based on the USB controller protocol, supports mice, keyboards and game controllers.
AVRCP - AV Remote Control Profile
Enables a smartphone to function as a remote control for computers and home theater equipment.
BIP - Basic Imaging Profile
Transmit images to external storage. Also used for remote controls and selfie sticks to snap a photo.
BPP - Basic Printing Profile
HCRP - Hard Copy Cable Replacement Profile
BPP supports printing without a printer driver, while HCRP requires a driver in the transmitting device.
CTP - Cordless Telephony Profile
Enables cellphones to connect to landlines in the home or office.
ICP - Intercom Profile
Always-on communications between two phones. See walkie talkie
IPSP/GATT - IP Support Profile/Generic Attribute
Internet IPv6 connectivity for low-power IoT devices. IPSP is direct, while GATT uses gateways. See Bluetooth 4.2