The LCD 16×2 can work in two distinct modes, in the 4 bit mode & 8 bit mode.
4 BIT MODE OF LCD
In 4 bit mode, we can send the 8-bit information in two half’s 4-bit (nibble) by 4-bit (nibble).
In 4 bit mode, we send the information/data nibble by nibble, first upper nibble transmitted from (D4-D7) and after that lower nibble transmitted from (D0-D3). A nibble is a group of four bits and a byte is a group of 8 bits. This enables us to send 8 bit of information/data.
8 BIT MODE OF LCD
In 8 bit mode, we can send the 8-bit information in one stroke.
Probably you get it, Yes 8-bit mode is quicker and impeccable than 4-bit mode. Yet, the significant disadvantage is that it needs 8 information lines associated with the microcontroller. This will make us come up short on I/O pins on our MCU, so 4-bit mode is broadly utilized.
NOTE: No control pins are utilized to set these modes. It is simply the method for programming that changes.
BYTE VARIABLE IN ARDUINO