What does a PIN Number and a PDF Format have in common? They both suffer from RAS Syndrome, also known as Redundant Acronym Syndrome. It’s when an acronym is followed by a word that is also part of the acronym, and there’s quite a couple of them.
Full details and more examples on Sketchplanations: https://sketchplanations.com/ras-syndrome
(fun fact: my grammar check actually tried to correct this post and tagged the PIN Number as "This phrase is redundant (‘N’ stands for ‘number’). Consider using “PIN”.")