Want to use the smallest Arduino board, or want to leave your arduino board embedded in project or the size and space are critical for your project? Then the Arduino Pro Mini is the solution.

The Arduino Pro Mini is a small microcontroller board  based on the ATmega 328.(datasheet), intended for use on breadboards and when space is critical. It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 8 analog inputs, and a 16 MHz crystal oscillator. It can be programmed with the  USB TTL serial adapter.

 Specifications

• Microcontroller: ATmega328
• Operating Voltage: 5V
• Input Voltage: 7-9 V
• Digital I/O Pins: 14 (of which 6 provide PWM output)
• Analog Input Pins: 8 (of which 4 are broken out onto pins)
• DC Current per I/O Pin: 40 mA
• Flash Memory: 16 KB (of which 2 KB used by bootloader)
• SRAM: 1 KB
• EEPROM: 512 bytes
• Clock Speed: 16 MHz

 To get your Arduino Pro Mini working, see this guide.