String prevent escaping on backslash

If you precede a string with the character @, then it makes it into a verbatim string.

Amongst other things, this means that escape sequences are read literally. So:

   string s = @"\t\n";

assigns a string consisting of a backslash, a 't', another backslash and a 'n' to the variable 's'.

If it hadn't been preceded by @:

   string s = "\t\n";

then it would have assigned a string consisting of a tab and a new line character to 's'.

You could have achieved the same effect as the verbatim string by simply doubling the backslashes which enables them to be treated as an ordinary character rather than an escape character prefix:

  string s = "\\t\\n"; // same effect as @"\t\n"