The Arduino Nano is Arduino's classic breadboard friendly designed board with the smallest dimensions. The Arduino Nano comes with pin headers that allow for an easy attachment onto a breadboard and features a Mini-B USB connector.
The classic Nano is the oldest member of the Arduino Nano family boards. It is similar to the Arduino Duemilanove but made for the use of a breadboard and has no dedicated power jack. Successors of the classic Nano are for example the Nano 33 IoT featuring a WiFi module or the Nano 33 BLE Sense featuring Bluetooth® Low Energy and several environment sensors.
The ATMega328 CPU runs with 16 MHz and features 32 KB of Flash Memory (of which 2 KB used by bootloader).
With a length of 45 mm and a width of 18 mm the Nano is Arduino's smallest board and weighs only 7 grams.
The Nano is made for breadboard use and features soldered headers for all pins, allowing to attach the board easily on any breadboard.