PS: You can follow “PS” with either a colon or a period. With our updated preference, the colon is best, but if you prefer “P.S.” you can leave it out.
Ing to the Cambridge Dictionary, the correct American format is 'P.S.' with periods after each letter. In contrast, the Chicago Manual of Style advocates PS without periods.
PS is widely used in letters and electronic communication like emails, text messages, instant messages, and social media. Although the punctuation of PS varies, it should always be capitalized. Make sure to punctuate it consistently in all your correspondence.
Add more postscripts by adding a 'P' to “PS.” The “post” in “postscript” means 'after' in Latin (and “script” means 'writing'), and so when you add another 'P' to a “PS,” you're writing an “after-after-writing.” PPS (and PPPs and PPPPS) is best used in informal correspondence to add a little bit of humor or cheekiness.