Universal asynchronous receiver-transmitter - Wikipedia
https://en.wikipedia.org/wiki/Universal_asynchronous_receiver-transmitter
A universal asynchronous receiver-transmitter (UART /ˈjuːɑːrt/) is a computer hardware device for asynchronous serial communication in which the data format and transmission speeds are configurable. It sends data bits one by one, from the least significant to the most significant...
Basics of UART Communication
https://www.circuitbasics.com/basics-uart-communication/
UART stands for Universal Asynchronous Receiver/Transmitter. It's not a communication protocol like SPI and I2C, but a physical circuit in a microcontroller, or a In UART communication, two UARTs communicate directly with each other. The transmitting UART converts parallel data from a controlling...