frontpage.xml - the homepage of your site example.com
postpage.xml - default article page template example.com/post-title-123456789.html
postpage_section-name.xml - article page template for posts in section-name section
search.xml - search page example.com/core/search/?q=search-query
subpage.xml - section page example.com/section-name
section_section-name.xml - section page template for section-name section
tagpage.xml - tag page example.com/tag-name
community/frontpage.xml - community user homepage
community/postpage.xml - community user article page
Keep global .xml reusable components here, such as the navigation bar or the sidebar of your layouts.
These are components specific to your article page. Whenever you need to add or modify info in your article template, search here for ready-made .html components such as the article's headline, name of author, article body, tags and others.
These are your posts blocks (such as the ones you see on the homepage or search results page), used to dynamically render posts results from your XML files, using the <posts> tag. You can create as many posts types as you need and render various data inside them.
These are ready made information blocks ready to be used in your posts .html files. All the information for your post title, thumbnail, author name, section title it belongs to and others are all coded in this folder. These files use variables from our global object, most of which you'll be able to see in your browser's dev tools, under the Bootstrap object.