Generated form asp-action tag helper includes id - asp.net

Question

I have the following form
<form asp-action="Edit">
<div asp-validation-summary="ModelOnly" class="text-danger"></div>
<input type="hidden" asp-for="Id" />
<div class="form-group">
<label asp-for="Title" class="control-label"></label>
<input asp-for="Title" class="form-control" />
<span asp-validation-for="Title" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="ReleaseDate" class="control-label"></label>
<input asp-for="ReleaseDate" class="form-control" />
<span asp-validation-for="ReleaseDate" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="Genre" class="control-label"></label>
<input asp-for="Genre" class="form-control" />
<span asp-validation-for="Genre" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="Price" class="control-label"></label>
<input asp-for="Price" class="form-control" />
<span asp-validation-for="Price" class="text-danger"></span>
</div>
<div class="form-group">
<input type="submit" value="Save" class="btn btn-primary" />
</div>
</form>
After running the project and going to Edit action view, i see in the source code in browser that <form asp-action="Edit">is translated into <form action="/Movies/Edit/2" method="post">
My question is, how does ASP know about the id (2) in "/Movies/Edit/2".

Answer 1

In this markup the ASP defines what is its ID to be passed in POST when its form is sent to the controller.
<input type="hidden" asp-for="Id" />
A hidden field allows your entity Id to be kept in the form without being seen or modified by users when a form is submitted.
See this documentation below as a supplement to your question.
https://learn.microsoft.com/en-us/aspnet/core/tutorials/first-mvc-app/controller-methods-views?view=aspnetcore-2.2
Thanks!

Answer 2

The edit form should always be delivered from an URL that has an ID in the URL according to our routing rules, something like /Movies/edit/1.
The form is always going to post back to that same URL, /Movies/edit/1.
The MVC framework will be able to pull that ID out of the URL and pass it as a parameter.
Refer to https://www.tutorialspoint.com/asp.net_core/asp.net_core_razor_edit_form.htm