c#: multiline string with @"..."

Question

When reading some Unity / C# code I saw a "@" in front of a multiline string:

  var configText = @"
    input_stream: ""in""
    output_stream: ""out""
    node {
      calculator: ""PassThroughCalculator""
      input_stream: ""in""
      output_stream: ""out1""
    }
    node {
      calculator: ""PassThroughCalculator""
      input_stream: ""out1""
      output_stream: ""out""
    }
    ";

What does the "@" do?