Feathers are the main/mother boards of the Feather platform.

You always need one Feather and can add zero or more FeatherWings to increase the capabilites.

For example:

• Feather Huzzah ESP8266 + Music Maker FeatherWing = MP3 streaming player
• Feather 32u4 Bluefruit + NeoPixel FeatherWing = Bluetooth LE controllable RGB lamp
• Feather 32u4 FONA + GPS FeatherWing = Cellular GPS locator with SMS control
• Feather nRF52 Bluefruit + Motor FeatherWing + Robot Chassis = Phone-controlled robot rover
• etc!

All Feathers...

• All Feathers have a microcontroller that can be programmed by Arduino IDE
• All Feathers are 3.3V logic
• All Feathers come with a MicroUSB or USB-C connector that is used for data and power
• All Feathers have a bootloader, and do not require a separate programmer device
• All Feathers have USB Serial for debug (sometimes it is part of a native USB interface, sometimes via a USB-serial adapter chip)
• All Feathers are 0.9" wide, and fit in a breadboard with 1 row available on one side, and two rows on opposite side.
• Almost all are 2.0" long (M0 ATWINC Feathers, FONA Feathers, and Hallowing M0 Express are the exceptions)
• All Feathers have the same two mounting holes near the USB port
• All Feathers have Power, I2C, SPI, UART pins in the same location. Remaining pins try to be as similar as possible (but they may have different pin names/numbers)
• All Feathers can run from USB or LiPo battery, and have a LiPo charger built-in

Most Feathers...

• Most of the Feathers have an Enable pin that will allow shutdown via logic level (Teensy and FONA Feathers are the exceptions)
• Most of the Feathers have a native USB connection (nRF52832 and ESP8266 are the exceptions)

Some Feathers...

• Some Feathers have a wireless module built in. Those that do not most likely can have an added FeatherWing to provide a radio.
• Only Feathers with "Express" in their name are fully CircuitPython Compatible.
• Feathers with a SAMD21 "M0" processor but not an "Express" board may run CircuitPython but must share the onboard flash with CircuitPython, restricting the space available.

No Feathers

• No feathers are guaranteed to be 5V-input compliant. Use 3.3V logic only please!