A post-it note is a small piece of paper with a re-adherable strip of glue on the back, allowing it to stick to surfaces without leaving residue. They are typically used for jotting down quick reminders, notes, or messages. Available in various colors and sizes, these notes are popular in offices, schools, and homes. Invented by Spencer Silver in the 1960s and later popularized by 3M, post-it notes have become a staple for organization and communication. Their convenience and versatility make them ideal for brainstorming sessions, to-do lists, and marking important pages in books or documents.