Bold, Italic, Underline and Strikethrough
These are problay some of the most common formatting buttons, familiar to anyone who has used a word processor. These formats are applied by selecting some text in the article and clicking the button in the editor toolbar and in the case of Bold, Italic and Underline, optionally by using the shortcut key.
Bold 
Renders the text with a strong emphasis which is usually heavier than surrounding text. Keyboard shortcut is CTRL + B
Will show in the HTML Source as <strong>text</strong>
Italic 
Italicises the selected text which usually appears slanted to the right. Keyboard shortcut is CTRL + I
Will show in the HTML Source as <em>text</em>
Underline 
Adds a line under the selected text. Keyboard shortcut is CTRL + U
Will show in the HTML Source as <span style="text-decoration:underline;">text</span>
Strikethrough 
Adds a line through the middle of the selected text
Will show in the HTML Source as <span style="text-decoration:line-through;">text</span>