Creating a “read more” link that extends the content on the page

Question

I would like to create a read more link that would extend a paragraph already being shown to reveal the entire text on the same page. If this could be solves with HTML5 and

Answer 1

More advanced version if your text is dynamic or coming from a database.

    
    
This is a paragraph.
    
This is another paragraph.
    
This is a very long paragraph...