The document discusses various types of pneumonia including community acquired pneumonia (CAP), nosocomial pneumonia, and atypical CAP. For CAP, the most common bacterial causes are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Nosocomial pneumonia is most often caused by Staphylococcus aureus or Pseudomonas in the ICU. Atypical CAP is commonly caused by Mycoplasma pneumoniae in young adults presenting with low-grade fever and cough.