What does "#" do after href?

Answer 1

If you mean this syntax: <a href="#">A link</a>, it has nothing to do with IDs. The '#' is used here as placeholder instead of real link/url. It makes a link clickable without taking you anywhere. Good for practicing and testing.

When you assign an ID to <a>, it will look like this:
<a id="fancy" href="#">link text</a>

The CSS is where you use '#':
a#fancy { color: orange; }

Answer 2

if you want to keep the user on same page even after clicking that anchor then you can use # after href like
<a href="#" >anchor</a>

Answer 3

when you link using id then u have to use # In href.

Answer 4

can I have an example please?

Answer 5

in css # is use to refer for id and . for class
eg
# {color:black;} change the color of the p tag.

Answer 6

placeholder, means to Shang the # to ur link

Answer 7

if you want to link with id's like

<p id="hello">hello world</p>

<a href="#hello">click</a>

mostly it's used in one page website or application