Html or xml code for the doctype, where it is located?

Hello;
Normally in web based application, for each form, there is html page. When we create doctype, where is the html or xml page that is corresponding for this form? Is it the task of the frappe to convert this form to html code when executing without having file that showing us the code?

If I can find this file, I can do customization from this file also.
Appreciate this kindly help and advise.
Regards
Bilal

Yes, its the objective of frappe to keep things simple. I believe there’s an html datatype If you want to add custom html or might as well use webpages https://frappe.github.io/erpnext/user/manual/en/website/web-page

@bghayad I read your question two different ways, let me restate so we can focus on what you’re looking for:

  1. ERPNext doctype information is stored as a JSON file. Frappe renders this JSON file with its rendering engine. If you wanted to look at it for the Item doctype for example, here’s the link:
    https://github.com/frappe/erpnext/blob/develop/erpnext/stock/doctype/item/item.json

  2. If you want to render HTML in a field within a doctype, that’s different (and hard). Here’s the best way I’m aware of, though I’d qualify that by saying that I haven’t gotten it working yet myself. There are a lot of moving parts.
    Bring Data into HTML field in the DocType