To connect LCD display 16×2 or 20×4 to Arduino you know you’ll need at least 6 wires to connect, it means sacrificing some IO’s that could be used for connecting other components such as sensors or motors. another way is to use 74HC595 Shift register for interfacing. In this tutorial we will discuss on PCF8574 I2C LCD Display Interface.
A module that can be used to circumvent this problem is the I2C Module for LCD Display with PCF8574 (datasheet ):