28+ Arduino Mega Pinout 2560 Background. The atmega2560p comes with builtin bootloader which makes it very easy to flash the board with your code. There are pin mappings to atmega8 and atmega 168/328 as well.

Arduino Mega 2560 Pro Pinout Circuit Boards
Arduino Mega 2560 Pro Pinout Circuit Boards from s1.bukalapak.com
With 54 digital pins,16 analog inputs and a larger space. As far as other hardware on the mega goes, it also touts four serial ports for general attachments, a usb connection (with a dedicated atmega16u2 processor for interfacing with your computer), a reset. Following figure shows the pinout of arduino mega 2560.

The atmega2560p comes with builtin bootloader which makes it very easy to flash the board with your code.

The mega2560 has 16 analog inputs, each of which provide 10 bits of resolution (i.e. See the documentation for details. First feature is the large i/o system design with inbuilt 16. The mega 2560 also supports twi and spi communication.