White blood cells (WBCs), or leukocytes, are essential components of the immune system that defend the body against infections, foreign substances, and abnormal cells. They are produced in the bone marrow and circulate in the blood and lymphatic system. WBCs are categorized into different types, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils, each playing a specialized role in immunity. They identify, attack, and destroy harmful pathogens like bacteria and viruses. For example, in bacterial infections, doctors often prescribe antibiotics such as ceftriaxone injection, which is supplied globally through ceftriaxone injection distributors, supporting healthcare systems in infection management and treatment.