choose one tab to identify yours from others in the household...tab is useful for grabbing to pull band to open

So if someone else in your group of e-readers have the same cover they can ID it by the color of the tabs...

Put the tab of your choice around the elastic band. It serves as an easier way to grab the elastic when opening or closing. Nothing more significant that that.

You use one of the colors on your Kindle and the others for other household members who have a Kindle so that you know which one is yours.

We each use a different tab color to quickly identify our own paperwhite.

They're supposed to be used to differentiate the cases for different family members. For instance, Dad gets a red tab on his, while Mom uses yellow, and Junior uses the third color. I really can't see multiple members of the same household having the same device size and buying the same cover. I would have liked having the choice of different colors for the entire cover - I am so tired of boring black!