Seven pairs are called true ribs. Each rib is attached to the breastbone in the front and curves around to join on to one of the vertebrae that make up the backbone via a strip of costal cartilage.
There are three pairs of false ribs. These are attached to vertebrae but are not linked to the breastbone. Instead, each rib is attached to the rib above it by cartilage.
There are two pairs of floating ribs. These are attached only to the vertebrae of the backbone.
All ribs are fragile but the floating ribs are especially fragile because these are attached only to the vertebrae of the backbone.
True ribs are ribs that are connected both at the back of the spine and at the sternum in front. false or floating ribs are not connected at the front which gives them less support and thus more easy to fracture.