In C, the main function typically takes two parameters: argc (argument count) and argv (argument vector). These parameters allow you to pass command-line arguments to your program.

Here's a simple example to illustrate how to use these parameters:

#include <stdio.h>

int main(int argc, char *argv[]) {
    // Check if there are command-line arguments
    if (argc > 1) {
        // Print the program name
        printf("Program name: %s\n", argv[0]);

        // Print the command-line arguments
        printf("Arguments passed:\n");
        for (int i = 1; i < argc; i++) {
            printf("%d: %s\n", i, argv[i]);
        }
    } else {
        printf("No command-line arguments passed.\n");
    }

    return 0;
}

In this example, argc represents the number of command-line arguments, and argv is an array of strings containing those arguments. argv[0] is the program name, and the subsequent elements (argv[1], argv[2], etc.) are the actual command-line arguments.

Compile and run the program with command-line arguments to see how it works. For example:

./program_name arg1 arg2 arg3

In this case, argc would be 4, and argv would be an array containing the program name and the three arguments.

Keep in mind that the main function's signature must be one of the following:

int main(void)

or

int main(int argc, char *argv[])

The return type can be void or int, and argv is an array of strings (char*).