sticky note

US /ˈstɪk.i ˌnoʊt/
UK /ˈstɪk.i ˌnoʊt/
"sticky note" picture
1.

a small piece of paper with an adhesive strip on the back, used for temporary notes or reminders

:
I wrote a reminder on a sticky note and put it on my monitor.
The whiteboard was covered with colorful sticky notes.