To add to the confusion, all I2C LCDs I've seen claim to be serial LCDs, so do UART LCDs, or SPI LCDs. They are all correct in their claims. Almost all the I2C LCDs I've looked online are just cheap port extenders. You will find that they are also the lowest-priced units since the port extender is so dirt cheap. You will have to use special libraries provided by the seller to drive your LCD and there are many different ones almost each having a different library (good luck with that). I design and sell LCD stuff and I stay away from I2C LCDs for my own reasons. You want to get a serial LCD that hooks up to your arduino serial port.