There have always been a few different ways of dealing with strings of text in C#, depending on what we need we might use any of the following;

string normalString = "This is a string, to include a line break we need to escape it like this \n so it doesn't terminate the string";

string verbatimString = @"This is a verbatim string where we can type enter
and the string contains the line break";

If we want to include variables in our string we have a few options again;

int x = 5;

string concatenation = "We can do this " + x " to include the variable";

string format = string.Format("We can do this {0} to include the variable", x);

string interpolate = $"We can do this {x} to include the variable";

The two interesting ones here are verbatim and interpolated strings.
If we need to build a multiline string with variables, perhaps from a template we can combine them like this.

var name = "Simon";
var templateName = "How to interpolate a verbatim string";
var now = DateTime.UtcNow;

var output = [email protected]"Hi {name},
This template is a demo of {templateName}.

It was ran at {now.ToString("o")}";

The output of the above demo is

Hi Simon,
This template is a demo of How to interpolate a verbatim string.

It was ran at 2017-04-11T14:46:09.5032168Z

For populating large multiline templates the ability to combine string interpolation with the formatting of verbatim string can be extremely useful