#include <stdio.h>: This header file provides functions and macros for performing input and output operations in C++. It includes functions like printf() for printing output on the console, scanf() for taking input from the user, and file I/O functions like fopen() and fclose() for reading from and writing to files. #include <stdlib.h>: The stdlib.h header file provides general-purpose functions for dynamic memory allocation, random number generation, string conversion, and other utility functions. It includes functions like malloc() and free() for dynamic memory allocation, rand() for generating random numbers, and atoi() for converting strings to integers. #include <time.h>: The time.h header file provides functions and structures for working with time and date in C++. It includes functions like time() for getting the current time, localtime() for converting the time into a more readable format, and strftime() for formatting time and date values as strings. #include <string.h>: The string.h header file provides functions for manipulating strings in C++. It includes functions like strcpy() for copying strings, strlen() for getting the length of a string, and strcmp() for comparing two strings. #include <unistd.h>: The unistd.h header file provides access to various POSIX operating system APIs, such as process management and system calls, in C++. It includes functions like fork() for creating child processes, exec() for executing other programs, and sleep() for pausing the execution of the program for a specified number of seconds. These header files allow you to use the functions and features defined within them in your C++ programs, making it easier to perform tasks like input/output operations, memory management, time manipulation, string manipulation, and system-level operations.