If it is necessary to indicate within a document that a particular text is no longer correct, accurate, relevant or acceptable, the HTML5 <s> tag has to be incorporated by the author.

It has to be noted that this has a different function compared to the <del> tag. The <del> tag is for suggesting that the text has been omitted and replaced. The HTML5 <s> tag is for showcasing that the details are no longer valid.

Interestingly, the HTML5 <s> tag has been considered as obsolete in HTML4.01. However, it is again reused for HTML5.

Using the HTML5 <s> tag is not complex at all because of its compatibility with Internet Explorer, Google Chrome, Safari, Opera and Firefox. It is also well-suited with the Global Attributes and Event Attributes in HTML5.