<P> A postscript (P.S.) is an afterthought, thought of occurring after the letter has been written and signed . The term comes from the Latin post scriptum, an expression meaning "written after" (which may be interpreted in the sense of "that which comes after the writing"). </P> <P> A postscript may be a sentence, a paragraph, or occasionally many paragraphs added, often hastily and incidentally, after the signature of a letter or (sometimes) the main body of an essay or book . In a book or essay, a more carefully composed addition (e.g., for a second edition) is called an afterword . The word "postscript" has, poetically, been used to refer to any sort of addendum to some main work, even if it is not attached to a main work, as in Søren Kierkegaard's book titled Concluding Unscientific Postscript . </P> <P> Sometimes, when additional points are made after the first postscript, abbreviations such as PSS (post-super - scriptum), PPS (postquam - post-scriptum or post-post - scriptum) and PPPS (post-post - post-scriptum), and so on, ad infinitum are used, though only PPS has somewhat common usage . </P>

Where is p.s. written in a letter