Bold

Use bold text when referring to buttons: Click Save.
In documentation, use bold font and a symbol, such as a pipe ( | ), to display menu option selections or sequences of user interface clicks. For example, File | Print indicates that a user selects the Print option from the File menu.
Include edition names in bold text in edition tables. For example: Enterprise Edition.
Never highlight a sentence in boldface text.

Salesforce.com Style Guide for Documentation and User Interface Text