Ruby On Rails : Why do we need to html_safe string? : Why html tags not rendered?

What is html_safe? Why use that? Read this

Lets say, you have a feature in your application such that you have a text-area (Integrated with text-editor plugin) in your form and use can write markups. These markups are supposed to be rendered in the view as HTML Tags (Just like they appeared in TextEditor like CKEditor). Suppose you write Continue reading