HTML attribute element provides additional information, most of the label property can be provided, generally located in the start tag, so as to name / value occurs, for example: name = "value".
The value to be placed in quotes (single, double quotes may be), if the value contains double quotes is necessary to use single quotes, for example: name = 'Jack "OJBK" Tom'
Example:
<a href="http://www.baidu.com">baidu</a>
Note: It is recommended to use lowercase attribute.
HTML standard attributes Reference Manual: https://www.runoob.com/tags/ref-standardattributes.html