what is this statement used for?

[san_crazy]

just like in C, format specifiers are used in both printf(), and scanf() functions.
in this C# statement

Console.WriteLine("{0}, {1}", intValue, longValue);

what does it mean by {0},{1}?
are these format specifiers?

regards
san

[DdoubleD]

Yes, it is similar to using %d or %l in C. Each enclosing numbered brace indicates it is a placeholder for the next parameter. Here is a good link on the construction of the format: http://msdn.microsoft.com/en-us/library/txafckwd.aspx

[serkan sendur]

it is formatting the output just as you said "formatters".

[papanyquiL]

It put's the values after the string into the numbers in the brackets specified. For example:

Console.WriteLine("{0}, {1}, {3}", dogValue, catValue, birdValue);

Your basically saying this:

Console.WriteLine("{dogValue}, {catValue}, {birdValue}");