Helper T cells are a type of white blood cell that play a crucial role in the immune system. They help coordinate the body's response to infections by signaling other immune cells, such as B cells and cytotoxic T cells, to take action against pathogens like bacteria and viruses. These cells are activated when they recognize specific antigens presented by antigen-presenting cells. Once activated, helper T cells release signaling molecules called cytokines, which enhance the immune response and help the body effectively fight off infections and diseases.