Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Anemia is the most common blood disorder characterized by hemoglobin deficiency or a low number of red blood cells. There are hundreds of types of this blood disorder, which is prevalent in developing countries and poor areas. The most common cause of anemia is iron deficiency, but the lack of vitamin B12, damages of bone marrow as well as specific inherited conditions and chronic diseases may cause the disorder. Learn more about the blood disorder as well as its types, causes and treatments in this book.