Cancer is a condition where abnormal cells multiply uncontrollably, disrupting normal bodily functions. Normally, cells divide for growth, repair, and maintenance, creating exact copies of themselves. However, in cancer, cells become abnormal due to unknown factors, leading to faulty division. These abnormal cells continue to multiply, forming lumps or ulcers in organs. In blood cancer, such as leukemia, abnormal cells circulate in the bloodstream, without visible lumps. Cancer can spread to other parts of the body through lymphatic channels or blood vessels, a process known as metastasis, making it challenging to treat once it has spread.