A string preceded with the $ character is called an interpolated string.
Interpolated strings can include expressions inside braces:
int x = 4; $"A square has {x} sides" // A square has 4 sides
C# will convert the expression to a string by calling its ToString method.
You can change the formatting by appending the expression with a colon and a format string:
string s = $"255 in hex is {byte.MaxValue:X2}"; // X2 means 2-digit Hexadecimal // "255 in hex is FF"
To use multi line interpolated strings, specify the verbatim string operator.
$ operator must come before @:
int x = 2;
string s = $@"this spans {
x} lines";
To include a brace literal in an interpolated string, repeat the desired brace character.