Arduino is an open-source hardware and software company, project and user community that designs and manufactures single-board microcontrollers and microcontroller kits for building digital devices.
Arduino Mega 2560 R3 is based on the ATmega2560 SMD chip. 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.
The Arduino Mega can be powered via the USB connection or with an external power supply. The power source is selected automatically.