(1) In C/C++ programming, attributes contain information or parameters that define object classes property and/or behaviors. (2) In HTML, an attribute is a parameter that defines a special property of an HTML element. Attributes are specified within start tags. For example, means that the element IMG has an attribute called “SRC,” which is assigned the indicated value. (3) In XML, an attribute is similar to HTML attributes, but describes additional properties on any XML element.