ASP .NET is Object Oriented Programing (OOP), because its part of .NET framework, so it take a full advantage of the OOP capability.
ASP.NET Web pages, known officially as Web Forms, web form are contained in files with .aspx extension.
A directive is special instructions on how ASP.NET should process the page. The most common directive is <%@ Page %>.
.NET framework contain Entity framework, WCF, … that user can take advantage of them for building a new website.