Ex uno plures!
Connect three of your Arduino's output pins to this chip, and the chip will provide 8 new outputs. Daisy-chain these chips together, and each chip in the chain adds 8 new outputs without using up any additional Arduino pins!
When you activate this chip's output-enable, its outputs go into a high-impedance off state while preserving the data in the underlying shift register. This enables neat effects like pulse-width-modulation. LED arrays are a popular application; independently control each LED out of several hundred!.
See the Arduino shift register tutorial at: http://bit.ly/2284726
QTY: 1 x 74HC595 - 8-Bit Latching Shift Register - 16-Pin DIP
Alternate Part Number: NTE74HC595