It offers the same connectivity and specs of the Arduino Uno board in a smaller form factor.

The ATmega328 provides UART TTL serial (5V) communication, which is available on digital pins 0 (RX) and 1 (TX).

The RX and TX LEDs on the board flash when data is being transmitted via the FTDI chip and the USB connection to the computer (but not for serial communication on pins 0 and 1).

The Arduino software includes the Wire library to simplify use of the I2C bus.

3rd-party boards often have a different voltage regulator / different USB-to-UART chip / different color solder mask, and some have a different USB connector or additional features, too.