What is Helper class in MVC?

                HTML Helper is just a method that returns a HTML string. The string can represent any type of content that you want. For example, you can use HTML Helpers to render standard HTML tags like HTML <input>, <button> and <img> tags etc. You can also create your own HTML Helpers to render more complex content such as a menu strip or an HTML table for displaying database data.

Differentiation SingleOrDefault() vs FirstOrDefault() in MVC

	Single()	SingleOrDefault()	First()	FirstOrDefault()
Description	Returns a single, specific element of a sequence	Returns a single, specific element of a sequence, or a default value if that element is not found	Returns the first element of a sequence	Returns the first element of a sequence, or a default value if no element is found
Exception thrown when	There are 0 or more than 1 elements in the result	There is more than one element in the result	There are no elements in the result	Only if the source is null (they all do this)
When to use	If exactly 1 element is expected; not 0 or more than 1	When 0 or 1 elements are expected	When more than 1 element is expected and you want only the first	When more than 1 element is expected and you want only the first. Also it is ok for the result to be empty

List of Global.asax events in mvc.

protected void Application_Start(object sender, EventArgs e)
       {

       }

protected void Session_Start(object sender, EventArgs e)
        {

        }

protected void Application_BeginRequest(object sender, EventArgs e)
        {
        }

protected void Application_AuthenticateRequest(object sender,EventArgs e)
        {

        }

protected void Application_Error(object sender, EventArgs e)
        {

        }

protected void Session_End(object sender, EventArgs e)
        {

        }

protected void Application_End(object sender, EventArgs e)
        {

        }

protected void Application_Start()
        {
            
        }

How many web.config files can have in a web application(Project)..??

You may have multiple Web.Config files in one Asp.Net Application, but only One Per Folder.

What are the different types of Results in MVC (.Net)?

There are 11 different response types which can be sent to the end user :-

1. ViewResult - Renders a specified view to the response stream
2. PartialViewResult - Renders a specified partial view to the response stream
3. EmptyResult - An empty response is returned
4. RedirectResult - Performs an HTTP redirection to a specified URL
5. RedirectToRouteResult - Performs an HTTP redirection to a URL that is determined by the routing engine, based on given route data
6. JsonResult - Serializes a given object to JSON format
7. JavaScriptResult - Returns a piece of JavaScript code that can be executed on the client
8. ContentResult - Writes content to the response stream without requiring a view
9. FileContentResult - Returns a file to the client
10. FileStreamResult - Returns a file to the client, which is provided by a Stream
11. FilePathResult - Returns a file to the client

Example:-

1. View Result: - 
              public ActionResult Home()
             {
                   return View();
              }
2. Partial View Result :-
            Public ActionResult AboutUs()
            {
                 return PartialView("Hi");
             }
3. Json Result :-
            Public ActionResult Home()
            {
                 return Json("hello from JSON");
            }