The Arduino Mega 2560 Microcontroller Rev3 is a microcontroller board based on the ATmega2560. It has 54 digital input/output pins (of which 14 can be used as PWM outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with an AC-to-DC adapter or battery to get started. The Mega is compatible with most shields designed for the Arduino Uno, Duemilanove, or Diecimila.
The Arduino Mega can be powered via the 1.5m USB Cable Type A to B or with an external power supply. Each of the 54 digital pins on the Mega can be used as an input or output, using pinMode(), digitalWrite(), and digitalRead() functions. It also has 16 analog inputs, each of which provides 10 bits of resolution (i.e. 1024 different values).
The Arduino Mega2560 has a number of facilities for communicating with a computer, another Arduino, or other microcontrollers. The ATmega2560 provides four hardware UARTs for TTL (5V) serial communication. The Arduino Mega2560 can be programmed with the free and open source Arduino IDE through a USB connection without needing any extra hardware thanks to its preburnt bootloader. You can also bypass the bootloader and program the microcontroller through the Cytron USB ICSP PIC Programmer header.