Temporary furniture
It could be that you moved into your first apartment and weren’t quite sure what style you were going to go for. Or perhaps you were saving up for the perfect piece of furniture to fill the space but needed something to hold your books in the meantime. Whatever the reason for the temporary furniture entering your home, chances are that it’s still sitting around, it’s plastic looking odd against your proper furniture.
You really should be getting rid of it by now. Unless you’ve lost all of your furniture in a freak natural disaster, in which case you’re allowed, stylish and simple wooden shelving or cupboards are readily available to fit whatever theme you are going for. It has the bonus of probably not falling over every couple of days as well.