1. Arduino Uno: This is the most popular and widely used Arduino board. It is based on the ATmega328P microcontroller and is commonly used for general purpose projects.
2. Arduino Mega: This board is based on the ATmega2560 microcontroller and is often used for projects that require more I/O pins, more memory, or more processing power than the Uno can provide.
3. Arduino Nano: This is a small form factor board based on the ATmega328P microcontroller. It is great for projects that require a small, low cost board.
4. Arduino Pro Mini: This is a very small form factor board based on the ATmega328P microcontroller. It is great for projects that require a very small board with limited I/O pins and processing power.
5. Arduino Due: This is a 32-bit board based on the Atmel SAM3X8E microcontroller. It is great for projects that require more processing power than the Uno or Mega can provide.
6. Arduino Zero: This is a 32-bit board based on the Atmel SAMD21 microcontroller. It is great for projects that require more processing power than the Uno or Mega can provide.