In our older guides on LCD display, we have shown the initial 1602A LCD Display Arduino Connection (Blue Light White Text 16×2), added a LDR to use that display to show intensity of light. But, that way of interfacing with Arduino is too primitive and engages too many pins. It is high inconvenient for repeated use and does not give all the features. We have software serial monitor on Arduino IDE. You Can Actually Convert Your Existing LCD to Serial With a Simple Module or By Using Components. Here is How To Convert LCD Display to LCD Serial Display For Arduino. I am not going to theoretical matters around I2C, serial monitor. Arduino has text on that serial matter :
How To Convert LCD Display to LCD Serial Display For Arduino
Basically adding a simple small circuit, sometime specific for the chipset of the LCD (like 1602A LCD) does the job. You can separately buy it and solder with LCD display or you can buy LCD display with I2C/TWI interface. If you are doing more than a simple project, you may be out of pins using a normal LCD shield. With this I2C interface LCD module, you only need 2 lines (I2C) to display information. This unit help to connect the LCD with 4 wires including Vcc and Gnd.
Of course you need a new library too and code will be like :
LiquidCrystal_I2C lcd(0x27,2,1,0,4,5,6,7); // 0x27 is the I2C bus address for an unmodified module
lcd.setBacklight(HIGH); // NOTE: You can turn the backlight off by setting it to LOW instead of HIGH
lcd.print("I2C Module Demo");
Obviously, it is possible to make that circuit of module o breadboard using basic electronic components. This information should be enough for most of the readers to perform web search and find tit-bits.