While writing code in MVC there are scenarios where you need to use one view in more than one action .

One way is to create separate view for it that will be a tedious process to do

Another way is to create a common view for multiple action

For doing that you need to write the method or action for it while selecting view you will make it a shared view

public class MenuController : Controller
{
    [ChildActionOnly]
    public ActionResult Header()
    {
        var model = ... // go to the database and fetch a model
        return View("~/Views/Shared/_Header.cshtml", model);
    }
}

You will return it wherever you want in your application

You will always create that view inside Shared folder which will make it sharable to other actions