What is the full form of P.S. ?

PS or P.S. - PostScript

PS or P.S., is writing added after the main body of a letter. After the fact, it allows you to add anything you forgot to mention in your message, book or an article.

          A postscript can be in the form of a line or a paragraph added after the signature of a letter. One of the famous movie's name included this term P.S. I Love You.