An HTML element is specified by a start tag. If the element comprises the other content, it closes with an end tag, where the element name is defined by a forward slash, you can see below the tags:
<p> </p> => This is paragraph content.
<h1> </h1> => This is heading content.
<div> </div> => This is division content.
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So, the above HTML elements have end tags, but, there are a few HTML elements which don't require to be closed, such as <img.../>, <hr /> and <br /> elements.
These are called as void elements.
HTML elements are characterized in a progression of unreservedly accessible open gauges gave since 1995, at first by the IETF and in this way by the W3C.
During the program wars of the 1990s, engineers of client operators (for example internet browsers) frequently built up their own components, some of which have been received in later measures. Other client operators may not perceive non-standard components, and they will be overlooked, perhaps making the page be shown inappropriately.
In 1998, XML (an improved type of SGML) acquainted systems with permit anybody to build up their own components and join them in XHTML records, for use with XML-mindful client agents. Therefore, HTML 4.01 was changed in a XML-perfect structure, XHTML 1.0 (eXtensible HTML).
The components in each are indistinguishable, and much of the time substantial XHTML 1.0 records will be legitimate or about substantial HTML 4.01 reports.
This article essentially centers around genuine HTML, except if noted in any case; in any case, it stays relevant to XHTML. See HTML for a conversation of the minor contrasts between the two.