How to comment in HTML program

Adding comment:

To create description about html code & not to be display this description in the browser when visitor visits to the site, <!-- --> tag can be used.It is helpful while editing code.
<!--and--> sequences are used to eliminate this effect.
Eg. <!--comment can be placed here-->.

Some HTML Do's and Don'ts:

* While you write HTML code, each tag opened must be closed with its respective tag.
For Eg., <b> and </b> tags.
First tag is called opening tag and other that begins with forward (/) slash is called closing tag.
The first tag turns the action on and the second turns it off.
There are some exceptions.
For instance, the <br> tag creates a blank line and doesn't have closing tag.
* When nesting tags i.e. when you start a tag within another tag, the inner most must be closed first. Like,
<head> <title>
You page title goes here </title></head>
Where following notation is wrong as per the HTML rules
<head> <title>
You page title goes here </head></title>

* Attributes values must be closed within double quotes ("") or single quotes ('').
It is required because your attributes value may contain multiple strings and such case if it is not quoted the second word in value is considered as attributes name and it may result in Error.