In this article, you will learn what is ValidateInput(bool) in ASP.NET Core
In this article, Passing HTML code via POST to a controller does throw an exception in older versions of ASP.NET(eg. MVC 5).
In asp.net core you may not need to add this attribute, because, by default, the validation is not so strict as in ASP.NET MVC 4 or 5
ValidateInput(bool) in ASP.NET Core