What is memory padding

main.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#pragma pack(8)
typedef struct Thing {
    int test;
    char k;
    char str[10];
    int* p;
    short sh;
} Thing;

int main(int argc, char* argv[]) {
    int i;
    Thing t = { 12, 'k', "testing", &i, 256 };
    printf("Size: %llu\n", sizeof(t));
    
    unsigned char data;
    for (i = 0; i < sizeof(t); i++) {
        if (i % 8 == 0) {
            printf("\n");
        }
        data = *(((unsigned char*) &t) + i);
        printf("%02x ", data);
    }
    return 0;
}