today I was given a board stm 32 NUCLEO-F302R8 and was asked to study about it. on internet, after some searching I got a documentation which was on this board.
So here are some details: Targeted MCU STM32F302RT6
Te purple mark indicates main stream board.

the communication between computer and the mcu or between two mcus is through UART i.e universal asynchronous reciever/transmitter.

there are 2 pins for data transfer

it sends or recieves data in form of chunks or packets(transmission characters)