Without this firmware the code found in the Arduino IDE would not be compatible with the microcontroller. It is the ICSP header that allows the microcontroller to receive the firmware or program that ...

While we certainly do love the Arduino Nano for its low-cost and versatility ... Rather than using the bootloader, ICSP (in-circuit serial programming) and DebugWire are possible alternatives ...

The new Arduino board's just been outed ... auto sensing / switching power input, ICSP header for direct program download, and a manual reset switch. Hit up the source link for a bit more info ...