The header HTML element represents introductory content, typically a group of introductory or navigational aids. It may contain some heading elements but also a logo, a search form, an author name, and other elements.
The main HTML element represents the dominant content of the body of a document. The main content area consists of content that is directly related to or expands upon the central topic of a document, or the central functionality of an application. Should be only main section!
The article HTML element represents a self-contained composition in a document, page, application, or site, which is intended to be independently distributable or reusable (e.g., in syndication). Examples include: a forum post, a magazine or newspaper article, or a blog entry, a product card, a user-submitted comment, an interactive widget or gadget, or any other independent item of content.
The aside HTML element represents a portion of a document whose content is only indirectly related to the document's main content. Asides are frequently presented as sidebars or call-out boxes.
The nav HTML element represents a section of a page whose purpose is to provide navigation links, either within the current document or to other documents. Common examples of navigation sections are menus, tables of contents, and indexes. on site there could be a few nav sections
The section HTML element represents a generic standalone section of a document, which doesn't have a more specific semantic element to represent it. Sections should always have a heading, with very few exceptions.
The address HTML element indicates that the enclosed HTML provides contact information for a person or people, or for an organization.
The footer HTML element represents a footer for its nearest ancestor sectioning content or sectioning root element. A footer typically contains information about the author of the section, copyright data or links to related documents.