The <aside> tag is newly introduced in HTML5. It represents content which is related to its surrounding content in a document, but it can still has individual importance. The <aside> element is usually used in sidebar of a document. For example it can be used for showing some quotes or important parts from a large article in the sidebar.
Web browser support:
HTML5 <aside> tag is supported by latest versions of all web browsers. Internet Explorer 8 or earlier versions of Internet Explorer do not support this element.
There is a HTML5 <aside> element example given below:
<article> <header> <h1>Taj Mahal India</h1> </header> <p>I have visited the Taj Mahal at Agra with my family in last year. It was a memorable experience.</p> <aside> <h4>Taj Mahal</h4> <p>The Taj Mahal was built by Mughal emperor Shah Jahan in memory of his third wife, Mumtaz Mahal in 17th century.</p> </aside> </article>