Snakes responsible for severe envenomations are considered a real public health problem, especially in tropical countries. Yet, snake venom, which is made up of hundreds of specific substances, is used more and more in biomedical research and as a diagnostic or therapeutic tool. This text first presents a synthesis of the principal discoveries on venoms and envenomations. Then paleontology and classification of snakes as well as the biochemistry and toxicology of venoms are simply and precisely described to explain the theoretical basis of the envenomation and its treatment. Knowing the biology and behavior of snakes leads to a better identification of the circumstances of snakebites and thus supports prevention efforts. Recommendations and algorithms of treatments are proposed. This reference also lists all the antivenins produced in the world and the antivenomous plants with their therapeutic properties.