The pinout diagrams are simple, but they're easy to read, and especially helpful for beginners. You can print them out full size so you can set your Arduino Uno, ATMega, or ATTiny right on top for ...

Note: Pin D9 on the Arduino is not the same pin 9 on the ATmega328 IC. Pin 15 on the IC is actually the pin for Digital Pin 9 (D9) on the Arduino. If you want to see the pinout for the ATmega328 IC, ...

Each of the 14 digital pins on the Arduino Uno can be used as an input or output, using pinMode(), digitalWrite(), and digitalRead() functions. They operate at 5 volts. Each pin can provide or receive ...

Then, chances are you already know what an Arduino is ... notice between the two boards' pinouts are that the Nano has more reset pins (two versus one on the Uno), fewer GND pins (two versus ...