In many cases, especially with large HTML code, we need to put some comments, so that we can remember what each part of code was intended for, if we or somebody else reviewed the code later, in other cases, we may enclose part of the code as a comment to prevent it from appearing in the browser for test reason.

To define a part of code as a comment, we need just to enclose it with the following brackets:
<!--  and -->

Let’s apply this to our code as the following:

<!doctype html>   
    <title>My  Learning Plan</title>
    <h1>Hi, I'm  learning HTML.</h1>
    <p>I will use it  for <i>developing web pages</i>.  
    It is very easy and simple.</p>
    <hr />
        <!-- Here I  will list my training plan for this year -->
        <p>This is <em>part of my learning plan</em>.  <u>
        Which will  include:</u></p>
        Html<br />
        JavaScript<br />
        And the Java Programming Language<br />

When we open the page in the browser the sentence “Here I will list my training plan for this year” will not appear in the browser, because it is just a comment.

So the output will look like the following: