Anaemia is defined as a low haemoglobin level. It can be classified based on the mechanism (decreased red blood cell production or increased red blood cell loss) and mean corpuscular volume (MCV). Common symptoms include fatigue, dyspnea, and palpitations. Signs include pallor, jaundice, and heart murmurs. History should focus on iron loss, diet, medications, and family history. Investigations include full blood count, reticulocyte count, blood film, iron studies, folate, B12, and bone marrow biopsy if needed. The most common cause is iron deficiency due to blood loss. Treatment depends on the underlying cause.