Notebook margins. Remember the horror of realizing that “college ruled” notebook paper meant slimmer margins, and therefore left room for more writing? Well, believe it or not, those margins weren’t invented as a guide for how many sentences you could fit onto one page, or even to leave space for note-taking. Manufacturers began to apply margins to writing paper for the purpose of protecting your work. Earlier on in history, rats were a common resident in many people’s homes, and one of their favorite snacks was your paper, in addition to everything else they could munch on. Applying wide margins to paper safeguarded against losing important work by leaving blank spaces around the edges for the rats to chew through first, and to protect the writing on the outer edges from general wear and tear.