A notepad is a pad of paper: several sheets fastened along one edge, used for writing notes. You often tear a page off. A notebook usually has a spine and stays together; a notepad is for quick writing you may throw away. You find notepads on desks, in meetings, by the phone. Though actually, for many students in Taiwan the first Notepad they meet is the Windows program 記事本, a simple place to type text. That computer sense is a later use of the same word: a digital pad for notes. In careful English, notepad is the paper thing unless you are talking about computers.

便條本；（電腦）記事本（Windows 的 Notepad）。跟有書脊、可長期保存的筆記本 notebook 不一樣。