A Post-it note (or sticky note) is a small piece of paper with a re-adherable strip of glue on its back, made for temporarily attaching notes to documents and other surfaces. A unique low-tack pressure-sensitive adhesive allows the notes to be easily attached, removed and even re-posted elsewhere without leaving residue. Originally small yellow squares, Post-it notes and related products are now available in a wide range of colors, shapes and sizes.