Minimal user role: contributor
Body fields and many other fields can hold formated text. The easiest way to enter formated text is by using the rich-text editor. You can enable/disable the rich-text editor by clicking on 'enable/disable rich-text' below the field. You can set the default for the rich-text editor by going to 'My account' under your user name clicking on 'TinyMCE rich-text settings' and setting the default there. Submit.
An explanation of the icons of the rich-text editor appears when the mouse hovers over them.
When you copy and paste text into the editor, line breaks and other formats are usually kept and may screw up your formating. However, this is only visible when disabling the rich-text editor or previewing the page. To avoid this, text can be pasted using the 'Paste as plain text' icon.