HTML attribute

HTML attributes are special words used to adjust the behavior or display of an HTML element. An attribute either modifies the default functionality of an element type or provides functionality to certain element types unable to function correctly without them. In HTML syntax, an attribute is added to an HTML start tag. Several basic attributes types have been recognized, including: (1) required attributes needed by a particular element type for that element type to function correctly; (2) optional attributes used to modify the default functionality of an element type; (3) standard attributes supported by many element types; and (4) event attributes used to cause element types to specify scripts to be run under specific circumstances. Doctype HTML is a declaration that tells the browser what version of HTML the document is written in. Some attribute types function differently when used to modify different element types. For example, the attribute name is used by several element types, but has slightly different functions in each.

HTML attributes are special words used to adjust the behavior or display of an HTML element. An attribute either modifies the default functionality of an element type or provides functionality to certain element types unable to function correctly without them. In HTML syntax, an attribute is added to an HTML start tag. Several basic attributes types have been recognized, including: (1) required attributes needed by a particular element type for that element type to function correctly; (2) optional attributes used to modify the default functionality of an element type; (3) standard attributes supported by many element types; and (4) event attributes used to cause element types to specify scripts to be run under specific circumstances. Doctype HTML is a declaration that tells the browser what version of HTML the document is written in. Some attribute types function differently when used to modify different element types. For example, the attribute name is used by several element types, but has slightly different functions in each. HTML attributes generally appear as name–value pairs, separated by = , and are written within the start tag of an element, after the element's name: element content Where element names the HTML element type, and attribute is the name of the attribute, set to the provided value . The value may be enclosed in single or double quotes, although values consisting of certain characters can be left unquoted in HTML (but not XHTML). Leaving attribute values unquoted is considered unsafe. Although most attributes are provided as paired names and values, some affect the element simply by their presence in the start tag of the element (like the ismap attribute for the img element ). The abbreviation element, abbr , can be used to demonstrate these various attributes: HTML This example displays as HTML in blue without being a link, and in most browsers, pointing the cursor at the abbreviation should display the title text "Hypertext Markup Language" within a floating yellow background (tooltip). Centered text In this other example, your text will look like this: Centered text Most elements also take the language-related attributes lang and dir . The class attribute provides a way of classifying similar elements. Multiple class names can be added by separating them with spaces. Semantically, for example, classes are used in microformats. Additionally, authors of style sheets can construct selectors that match elements by class for styling purposes. For example, a HTML document might use the designation class="notation" to indicate that all elements with this class value are subordinate to the main text of the document. Such elements might be gathered together as footnotes on a page—instead of appearing in the place suggested by their position within the HTML source. The style sheet author might also define a rule with the .notation selector and define the property font-size: small; . The style attribute provides a way of applying element-specific style rules. Multiple style declarations can be added by separating them with semicolons and an optional space, where each declaration includes a CSS property name and a value separated by a colon and an optional space (Example: style="color: red; text-align: center;" ). The style attribute can be used on any HTML element (it will validate on any HTML element; however, it is not necessarily useful). It is considered better practice to add the style information to a style sheet, often accomplished with selectors that match the element class or ID. Sometimes, however, inline styles are favored where style sheets are considered too cumbersome for a simple and specific or ad hoc style specification. The title attribute is used to attach subtextual explanation to an element. In most browsers this attribute is displayed as what is often referred to as a tooltip.

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