To format the current paragraph:

• gqap
• gwap same, but restores cursor position

Comments

 TO DO 

• Thanks to anon who pointed out that gwap makes the original tip obsolete (I have removed it).
• We don't have any other tips that explain basics of paragraph formatting, so this may as well be it.
• Need to explain what "format" means here.
• Need to mention textwidth, formatexpr, formatprg and probably more (but keep it simple).