STARTTAG

Starttag, or opening tag, is the markup token that begins an element in markup languages such as HTML and XML. It identifies the element name and may include attributes that describe properties or behavior. The start tag is typically paired with a corresponding end tag, or it may be self-closing in certain languages.

Syntax and structure: A start tag is written with angle brackets, the element name, and optional attributes, for example: <div class="container" id="main">. In many languages, the start tag is closed by a separate end tag written as </div>, which marks the end of the element’s content. Some languages also allow a self-closing form to denote an empty element, written as <tagname attributes/>. In XML, every element must have a start tag and an end tag or be self-contained; in HTML, the rules are more flexible and include void elements that do not require end tags.

Differences across languages: In XML and XHTML, the syntax is strict and attributes must be quoted, and empty elements are written with a self-closing tag. In HTML, there are void elements such as <br>, <img>, and <hr> that do not have end tags and do not contain content. HTML also includes rules where certain end tags can be omitted due to parsing behavior, whereas XML requires explicit end or self-closing tags.

Function and usage: The start tag announces the element to the parser and carries attributes that affect presentation, behavior, or semantics. The content that follows begins after the start tag and ends at the corresponding end tag, unless the element is void or self-closed. The start tag helps define the document structure and is part of the element’s position in the document object model.

Examples: A link: <a href="https://example.com" class="external">Example</a>. An image: <img src="image.png" alt="desc" />. A paragraph: <p>Text</p>.