便利贴（sticky note），或称自黏便笺、粘滞便笺、自粘便签、利贴（post-it note，报事贴）、易事贴，一种文具用品，可重复使用、背面上缘有胶的正方形或长方形纸片，用于正面书写文本，并贴附在文档、书籍、白板、桌面、电脑屏幕、家电用品或任何一种平坦的表面上。于1980年代由3M公司首先开始大量制造。

虽然3M公司拥有的专利已于1997年后失效，但“Post-it”及其中文商标名，于中国与香港，商标名为报事贴，在**，商标名为利贴，仍然还不是通用商标，3M公司仍然拥有商标权。**聚和国际也独立研发了类似产品，名为N次贴（Stick'N）。

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 an array of colors, shapes and sizes.