When you want to print an expression to an output device, you must specify the type of the expression and how you want it to be formatted. Conversion specifications are the symbols you use in the printf() control string to do this. Each expression whose value you want to output must have a corresponding conversion specification in the control string.

Conversion specifications for printf() and their uses:

Conversion Specification Output
%c character
%s string of characters
%d or %i decimal integer
%e floating point number in e-notation
%f floating point number in decimal notation
%g uses %f or %e whichever is shorter
%p pointer
%u unsigned decimal integer
%o octal integer
%x hexadecimal integer, using lower case
%X hexadecimal integer, using upper case
%% Prints a % sign

Here is an example of printf() using conversion specifications and another notation: 

#include 
void main()
{
        int numa, numb;
        numa = 1;
        numb = 2;

        printf("this is ");
        printf("on %d line", numa);
        
        printf(" even though we used more than 1 printf() function\n");

        printf("However, This \nwill be on %d lines", numb);
}
Output:
        this is on 1 line even though we used more than 1 printf() function
        However, This
        will be on 2 lines
You may notice that the "\n" caused a line break. This is called an escape sequence. The following is a list of the escape sequences:

Escape Sequences Meaning
\n New break
\a Alert. Plays a system beep
\b Backspace
\f Form feed
\r Carriage return
\t Horizontal tab
\v Vertical tab
\\ Prints a \
\' prints a '
\" prints a "
\0oo Prints an octal value (o represents an octal digit)
\xhh Prints a hexadecimal value (h represents a hex digit)