The terms former and latter are words used to distinguish between two things. Former directs us to the first of these two things, and latter directs us to the second (or last) of them. Do not use former or latter when you are writing about more than two things.
Former and latter are words that sound old-fashioned to some people, and indeed they are very old words.
According to the Online Etymological Dictionary, former derives from the Old English word forma, meaning “first.” By the 12th century, former was used to mean “first, earliest in time or order,” and by the 1580s, it arrived at its present meaning, “the first of two.”Latter has a similar history.