ID selectors may be used as an attribute to a tag. An ID selector is a string preceded by a hash mark (#), and is called using the ID= attribute. The hash mark does not appear in the value of ID. Works like the class selector except that the ID can be used only once in the document.
<style>#i5 {color: red;}</style>This is text with an ID of 'i5'.
This is text with an ID of 'i5'.