Initialization, as the name implies, is the initial configuration, and different uses have different configurations. If only one LED is lit, it is unnecessary for the program. If a timer is used, set baud rate, interrupt, etc. , then you must initialize. Of course, initialization does not have to be written as a function. It can also be written directly into the process of the main function, but it can be put into a function alone to facilitate the reading of the program.