string interpolation - C# reference | Microsoft Docs
docs.microsoft.com › en-us › dotnetJan 25, 2022 · Beginning with C# 10, when an interpolated string is used, the compiler checks if the interpolated string is assigned to a type that satisfies the interpolated string handler pattern. An interpolated string handler is a custom type that converts the interpolated string into a string. An interpolated string handler is an advanced scenario, typically used for performance reasons.