Using 74HC165 shift register with Arduino Uno

Hi, I've just bought two 74HC165 shift registers. They are labeled as parallel-in/serial-out. How can these be used with an Arduino Uno to control multiple outputs or inputs? Thanks!

The 74165 would be used to have 8 inputs that you can read via a synchronous serial input. You need 3 signal wires to connect the 165 to Uno. Clock, Shift/load, and Output. You can cascade 165's by connecting the output of one to the serial input of another. To use, send a low pulse to the shift/load input to latch the inputs into the shift register. Then use shift in to bring the data into the Uno.