ARTICLE
he article element represents a component of a page that consists of a self-contained composition in a document, page, application, or site and that is intended to be independently distributable or reusable, e.g. in syndication. This could be a forum post, a magazine or newspaper article, a blog entry, a user-submitted comment, an interactive widget or gadget, or any other independent item of content.
SECTION
The section element represents a generic document or application section…The section element is not a generic container element. When an element is needed for styling purposes or as a convenience for scripting, authors are encouraged to use the div element instead.
SECTION
a composition that forms an independent part of a document, page, application, or site. This could be a forum post, a magazine or newspaper article, a Web log entry, a user-submitted comment, an interactive widget, or any other independent item of content
ASIDE
! The aside element represents a section of a page that consists of content that is tangentially related to the content around the aside element, and which could be considered separate from that content. Such sections are often represented as sidebars in printed typography.
Authors are encouraged to use the article element instead of the section element when it would make sense to syndicate the contents of the element.