// It stands for "standard input-output" header, a C standard library.
// These are it's 4 most used functions:
    printf(); // Function used to show data on screen.

    scanf(); // Function used to get data from user.

    fprintf(); // Function used to press data in a file.

    fscanf(); // Function used to read data from a file.

// Discover more: https://en.wikipedia.org/wiki/C_file_input/output