Anticancer agents are substances used to prevent, inhibit, or treat cancer. They work by targeting cancer cells, disrupting their growth and division. These agents can be classified into various categories, including chemotherapy drugs, targeted therapies, and immunotherapy. Each type has a different mechanism of action and is chosen based on the specific type of cancer and its characteristics. Many anticancer agents are derived from natural sources, such as plants, while others are synthesized in laboratories. Common examples include cisplatin, a chemotherapy drug, and trastuzumab, a targeted therapy for certain breast cancers. Ongoing research aims to develop new and more effective anticancer agents to improve patient outcomes.