Its a C# thing - it means interpret the string literally or 'as is' .. that is to say
String myFilePath1 = @"Drive:\Path\File.Ext";
Won't cause an error - the "\P" and "\F" are not interpreted, but
String myFilePath2 = "Drive:\Path\File.Ext";
WILL cause an error because "\P" and "\F" are not recognised/a valid escape sequence - you have to make it
String myFilePath2 = "Drive:\\Path\\File.Ext";
without the '@' sign
'g'