“Pneumococcus” is not a disease name—it refers to the bacterium Streptococcus pneumoniae. This organism can cause pneumonia, ear infections, sinusitis, meningitis, and invasive bloodstream infections such as bacteremia or sepsis. The term “pneumococcal disease” describes the group of infections caused by this bacterium. Higher-risk groups include adults aged 65+, people with chronic medical conditions, immunocompromised individuals, and young children. Pneumococcal vaccines play a major role in reducing the risk of severe disease in eligible populations. Vaccination recommendations should be individualized based on age and risk profile under clinical guidance.