MISO is a communication line used in SPI protocol to transfer data from the slave device to the master device.

MOSI is a unidirectional communication line used in SPI communication protocols for transmitting data from the master to the slave device.

MQTT is a lightweight, open-source messaging protocol for constrained devices and low-bandwidth, high-latency networks.

A microcontroller unit (MCU) is a compact integrated circuit designed to govern a specific operation in an embedded system.