What is the difference between the `<aside>`, `<article>`, and `<section>` elements in HTML?

• <article>: A self-contained, independent piece of content that can be distributed and reused outside the current page context (e.g., a blog post, news, comment). It should have a heading inside.
• <section>: A thematic section of the page content. Usually has a heading (<h1>-<h6>) and groups related content. It should not be used just for styling — for that, <div> is used.
• <aside>: Content indirectly related to the main content of the page. Often used for side panels, inserts, advertisements, or quotes.

Comparison in a table:

Element	Purpose	Self-contained	Requires a heading (not strictly, but recommended)
<article>	Independent, portable content	Yes	Recommended
<section>	Thematic section within a document	No	Recommended
<aside>	Indirectly related content (sidebar)	No	No