How to exactly know what to write and edit in xml files of magento. I mean if we are making a module or a theme how to exactly edit the xml files.
e.g If we need a header we just write tag in html. I mean is there a specification for every tag that is being used and why?
P.S : I have used XML for only showing data in table format.
If you are looking for XML for the frontend module like a theme in Magento 2, you need to understand and follow the layout instructions to wireframe the page. Follow the below guidelines:
https://developer.adobe.com/commerce/frontend-core/guide/layouts/xml-instructions/ https://developer.adobe.com/commerce/frontend-core/guide/layouts/