Malaria is caused by the Plasmodium parasite, which is transmitted to humans through the bites of infected female Anopheles mosquitoes. There are five species of Plasmodium that can infect humans: Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, Plasmodium malariae, and Plasmodium knowlesi. Among these, Plasmodium falciparum is the most deadly and responsible for the majority of malaria-related deaths worldwide.