When entering text into the Rich HTML Editor with SharePoint 2010, you get a rich ‘ribbon’ experience, with a whole swag of stuff you can do – aptly titled “Format Text”.
This works for the Content Editor WebPart – and HTML content fields, such as Site Column – or Content Type column – like on a Publishing Page for example.
The editor includes a bunch of ‘tab groups’ (font, paragraph, etc) – with individual actions in each – like Bold, Italic, Underline, and so forth.