The Adafruit nRF52 core defines a number of custom classes that aim to make it easy to work with BLE in your projects.

The key classes are listed below, and examined in more detail elsewhere in this learning guide:

• AdafruitBluefruit is the main entry point to the Adafruit Bluefruit nRF52 API. This class exposes a number of essential functions and classes, such as advertising, the list of GATT services and characteristics defined on your device, and connection status.
• BLEService is a wrapper class for BLE GATT service records, and can be used to define custom service definitions, or acts as the base class for any service helper classes.
• BLECharacteristic is a wrapper class for a BLE GATT characteristic record, and can be used to define custom characteristics, or acts as  the base class for any characteristic helper classes.
• BLEDis is a helper class for the DIS or 'Device Information Service'.
• BLEUart is a helper class for the NUS or 'Nordic UART Service'.
• BLEBeacon is a helper class to configure your nRF52 as a beacon using the advertising packet to send out properly formatted beacon data.
• BLEMidi is a helper class to work with MIDI data over BLE.
• BLEHidAdafruit is a helper class to emulate an HID mouse or keyboard over BLE.