This id attribute can use for any of HTML element. These are case-sensitive id values we need to identify that case-sensitive manner and this id require at least one character. While creating id values we need not to give spaces, commas, etc.
In Html element can only have one unique id that belongs to that single element to use, using of class name can also be use multiple times in elements.
This is basic schooling level.
This is Junior schooling level.
This is advanced schooling level.