HTML attribute

An HTML attribute is a modifier of an HTML element type. 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 a large number of element types; and (4) event attributes, used to cause element types to specify scripts to be run under specific circumstances.

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.

Description

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: