The underline tag <u> will make a text underlined, so if you like to make the phrase “Which will include:” underlined in the following example, surround it by the <u> tag:

<!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>
    <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 />

The result will be as follows: