The MacOS Stickies app gives you stickers to your desktop, makes your Mac a virtual bulletin board and lets you write down short pieces of text to remember later. The notes are desktop-specific, so you can organize them as you want, and they retain their layout and content even after closing the app.
Getting Started with Stickies
Stickies is an old app and recent versions of macOS have buried it in the "Other" folder, along with many other tools. You can start this from here or by searching for it in Spotlight.
Immediately you will be presented with two examples of notes that contain some instructions and shows how Stickies will look at the desktop.
You can either edit These notes or close them and create your own by choosing File> New Note (or by clicking Command + N).
After you have made a new note, you can write what you want and use any formatting you would use in the TextEdit or Notes app.
Stickies can be buried under any window you have opened, so you can always set them upside down by turning on "Float on Top" from the window menu. 19659009] You must do it for each note, so you can use + Command + F to save a little.
If you do not want the notes to block your screen, you can make them transparent from the same menu or with options + command + t. You can also collapse them from the window menu or with the + M command or by double-clicking the title bar in the note: 
This is useful and makes your notes much smaller and allows you to retain more of them on the desktop without affecting your use of the rest of the system. You can also sort them automatically and have them sorted in a list at the top left, with the "Sort by" menu in the window.
Although there is no option to change where it is arranged, because the upper left position blocks the title bar on many apps, it is still a quite useful feature for keeping track of things.
You can also change the color from the "Color" menu or by command + 1 to command + 6:
You are limited to the classic Post-It colors, but there is enough for someone basic categorization.
Save your notes
Stickies automatically save each edit you to your notes so you may want to close the app or restart your Mac without losing anything. The only way to get rid of a note permanently is to click the box in the upper left corner of the note. This asks you to save when you try to close the note so that you can save the content as a text file. There are no "Save" options in the File menu, but you can use "Export Text", which will do the same.
If you'd rather switch to the Notes app, you can export all your current Stickies into Notes from the File menu by selecting "Export All to Notes."
They will appear in the Notes app under a new folder called "Imported Notes."
 Some things may look a little different, but they should keep their formatting and sorted by their colors in separate folders.