The Arduino Nano is similar to the Arduino Uno in as far as it provides you with great potential to build awesome devices but, is more compact. The Aruino Nano is designed to fit in small locations, has all the onboard components to keep it running without the bulk of a big PCB. 

Based on the ATmega328 microcontroller, the breadboard-friendly Arduino Nano offers a total of 14 digital I/O channels, 6 of which are PWM I/O, as well as 8 analog inputs. The board runs at 16 MHz clock speed and utilizes 32kB of flash memory – with 2KB reserved for operating the bootloader. 

The Arduino Nano V3 (CH340) is a microcontroller board based on the ATmega328 microcontroller. It is a compact version of the Arduino UNO, and it is popular for its small size and low cost.

The Arduino Nano V3 (CH340) has a number of features that make it easy to use and versatile. It has a microcontroller that can be programmed using the Arduino Integrated Development Environment (IDE), which is a free software tool that allows you to write and upload code to the board. The board also has a number of input/output (I/O) pins that can be used to connect sensors, actuators, and other devices to the board.

The Arduino Nano V3 (CH340) is an open-source platform, which means that the hardware and software designs are publicly available and can be modified by anyone. This has made it a popular choice for hobbyists, educators, and professionals, and it is used in a wide range of projects around the world. It is particularly well-suited for projects where size and cost are important considerations.

1.12 digital input / output port D2 to D13
2.8 analog inputs A0 ~ A7
3.1 pairs TTL level serial transceiver port RX / TX
4.6 PWM port , D3 , D5, D6, D9 , D10 , D11
5. Atmel ATmega328P - AU MCU
6 USB download and power
7. Support the external 5V ... 12V DC power supply
8. To support 9V battery powered
9 support ISP download