HTML tag

An HTML tag is a piece of source syntax that identifies the start or end of an HTML element. A start tag can contain HTML attributes; an end tag identifies a closing point under the parser's rules. The tag is source notation, while the resulting element is an object in the Document Object Model.^[ref]

For example, <p class="note">Hello</p> contains a paragraph start tag, text content and a paragraph end tag. Parsing it produces one paragraph element, not two elements corresponding to the two tags. Its text is represented separately in a DOM text node.

An HTML void element such as br has no end tag in HTML syntax. Some other elements permit tags to be omitted in specified contexts, so counting start/end pairs is not a complete account of the parsed structure. A trailing slash is also governed by HTML's own rules; it does not generally turn an ordinary HTML element into a self-closing XML-style element.^[ref]

Source context matters. Escaping < as < can make a tag-shaped example become displayed text instead of active markup. Programs explaining or transforming documents therefore need to distinguish the source syntax they are reading from the document structure that a parser constructs from it.