The id attribute

Because you’ve already used ids on <a> elements, and because you already know how to use a class attribute, you’re not going to have to learn much to use the id attribute. Say you have a footer on your page. There’s usually only one footer on any page, so that sounds like the perfect candidate for an id. Here’s how you’d add the identifier “footer” to a paragraph that contains the footer text:

Giving an element an id is similar to adding an element to a class. The only differences are that the attribute is called “id”, not “class”, an element can’t have multiple ids, and you can’t have more than one element on a page with the same id.