Backslash
// The filename will be c:\myfile.txt in both cases
string filename = "c:\\myfile.txt";
string filename = @"c:\myfile.txt";
The second example uses a verbatim string literal, which doesn't treat the backslash as an escape character.
Quotes
string text = "\"Hello World!\", said the quick brown fox.";
string verbatimText = @"""Hello World!"", said the quick brown fox.";
Both variables will contain the same text.
"Hello World!", said the quick brown fox.
Newlines
Verbatim string literals can contain newlines:
string text = "Hello\r\nWorld!";
string verbatimText = @"Hello
World!";
Both variables will contain the same text.