There are 4 types of wood or wood/glue that are commonly used in the cabinet and furniture industry. These are solid timer, plywood, particle board and mdf or medium density fibreboard.
I only use solid lumber and a good cabinet grade of plywood. I mention the the other two in this module just so you are aware of what is out there.
Unfortunately, most do not realize that the beautiful piece of furniture they purchased is made of mdf or particle board with a veneer. It may last quite some time but eventually it will chip, the shelf pegs will no longer hold, the shelves themselves will start to sag or the veneer will start pulling up.
These materials are manufactured mainly for the purpose of keeping costs down but in doing so the quality is compromised.