Final answer:
Most adults have 12 pairs of ribs which make up their rib cage, protecting vital organs like the heart and lungs.
Step-by-step explanation:
Most adults have 12 pairs of ribs as part of their rib cage or thoracic cage. This structure is vital as it encloses and protects organs such as the heart and lungs. The ribs are categorized into true ribs, false ribs, and floating ribs. The first seven pairs, known as true ribs, connect directly to the sternum. The following three pairs of false ribs connect to the sternum indirectly through cartilage linked to the ribs above. The last two pairs are the floating ribs, which are not connected to the sternum at all but are attached to the muscles of the abdominal wall.