The article element represents a complete, or self-contained, composition in a document, page, application, or site and that is, in principle, independently distributable or reusable.
The section element represents a generic section of a document or application. A section, in this context, is a thematic grouping of content, typically with a heading.
The nav element represents a section of a page that links to other pages or to parts within the page: a section with navigation links.
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.
The header element represents a group of introductory or navigational aids.
The footer element represents a footer for its nearest ancestor sectioning content or sectioning root element. A footer typically contains information about its section such as who wrote it, links to related documents, copyright data, and the like.
The menu element represents a toolbar consisting of its contents, in the form of an unordered list of items (represented by li elements), each of which represents a command that the user can perform or activate.
The main element represents the dominant contents of the document.
The div element has no special meaning at all
The em element represents stress emphasis of its contents.
The strong element represents strong importance, seriousness, or urgency for its contents.
The small element represents side comments such as small print.
The cite element represents the title of a work (e.g. a book, a song, a film, etc.).
The abbr element represents an abbreviation or acronym, optionally with its expansion (with title attribute).
The time element represents its contents, along with a machine-readable form of those contents in the datetime attribute.
The i element represents a span of text in an alternate voice or mood, or otherwise offset from the normal prose in a manner indicating a different quality of text.
The b element represents a span of text to which attention is being drawn for utilitarian purposes without conveying any extra importance and with no implication of an alternate voice or mood, such as key words in a document abstract, product names in a review, actionable words in interactive text-driven software, or an article lede.
The u element represents a span of text with an unarticulated, though explicitly rendered, non-textual annotation.
The span element doesn't mean anything on its own.
The script element allows authors to include dynamic script and data blocks in their documents.
async and defer are boolean attributes that indicate how the script should be evaluated. Classic scripts may specify defer or async, but only when the src attribute is present.
With <script>, parsing is interrupted by fetching and execution.
With <script defer>, fetching is parallel to parsing and execution takes place after all parsing has finished.
With <script async>, fetching is parallel to parsing but once it finishes parsing is interrupted to execute the script (potentially before parsing completes).
The story for <script type="module"> is similar to <script defer>, but the dependencies will be fetched as well.
The story for <script type="module" async> is similar to <script async> with the extra dependency fetching. (The defer attribute has no effect on module scripts.)
