meaning of href="#" and use of <!-- --> within style tag.

Dear Sir,
I have just started css.
What is the purpose of href="#" in the following code
which I found in mydivexample.html
<a href="#" class="style5" id="active">About us </a></li>
I thought href attribute always requires some url.

And also I want to know the reason why you have added
<!-- --> within <style> and </style> which I again found in the same example. Will it not ignore all the styles?

thank you sir

Hi


<a href="#" class="style5" id="active">About us </a>

You want link a text, EX: About us, contact us, services like this 3 tab you have but for that page is not yet created , so that time link you can put " # " this will link the text but it wont take that page, after preparing other pages replace # to correct link like about us.html, contact us .html

Regards