What is the use of id

Answer 1

You can specify a unique ID to most HTML tags to make them easily accessible in CSS and JS. If you gave your tags an ID, you can point a styling rule to that specific tag to only style that element, or be able to reference them in Javascript when they need to be modified.

Answer 2

Yeah, they be can said as a unique address to each HTML element. It makes document manipulation through JQuery or JavaScript really easy if you have a defined ID for that.