Text formats are composed of a series of filters and change how HTML tags are processed and displayed on your site. When a user creates content, the text format is associated with the content, and the full, original text is stored in the database. The content is then passed through filters in the text format before it becomes output on the site.
Each text format is associated with a visual WYSIWYG (What You See Is What You Get) HTML editor. The core Text Editor gives you the ability to configure the editors (such as adding and removing buttons from their toolbars). The core CKEditor module provides you with the industry-standard known as CKEditor, so it can be used to modify HTML content on your site.
There are three different editing modes you can use for CKEditor, Basic HTML, Restricted HTML, and Full HTML text formats. Each text format has an associated permission, so that you can pick and choose what user can use which text format. This filters certain users from using Basic HTML, which filters out dangerous HTML tags.
Basic HTML
Basic HTML provides the ability to add some basic text formatting to your document. When enabled, it adds the Bold, Italic, Underline, Strikethrough, Subscript and Superscript toolbar buttons that apply these styles.