Snakes are a very diverse and widespread group of animals. They occur in a wide variety of habitats, which requires specific adaptations. Like a lot of other activities, adaptations regarding reproduction had to evolve as well, in order to ensure successful embryonic development Most snakes reproduce once a year, after hibernation. Temperature was the main factor for development of different reproductive modes. The first mode is ovipary. Oviparous snakes lay eggs which are incubated outside of females’ bodies before the completion of embryotic development. The second mode is vivipary. Viviparous snakes keep their embryos inside their body until the end of its development. This form occurs in colder areas, where lower temperatures could adversely affect embryonic development within eggs exposed to environmental conditions. The third form is ovivivipary, which contains features of both ovipary and vivipary. Ovoviviparous snakes produce eggs and there is no direct transport of nutrients between the mother and the embryo. But in the end of its development, the embryos emerge from the eggs inside the mothers’ bodies and are born as in viviparous species. Temperature is generally very important for the life of snakes as it affects their activity and metabolism. Humidity and food availability are also important environmental factors influencing snake reproduction.