Cancer is characterized by abnormal cell growth and the ability to invade nearby tissues. The most common cancers worldwide are lung, breast, and colorectal cancers. In India, the four most common cancers are oropharynx, esophagus, stomach, and lung cancers in men, and breast, cervix, oropharynx, and esophagus cancers in women. Environmental factors like tobacco, alcohol, viruses, radiation, and genetic factors contribute to cancer development. Cancer control involves prevention, early detection, treatment, and rehabilitation efforts. Breast and cervical cancers are significant issues, with screening and education helping address them.