There are many types of snails, but they differ basically because they are aquatic or terrestrial. The former are adapted to life in the sea or bodies of fresh water, but the latter live exclusively on land, although in humid areas.
All land snails are gastropod mollusks, this means that they belong to the same group of octopuses, which is the Mollusca phylum. At the same time, they are members of the Gastropoda class, where all the snails and the so-called "slugs" are included. Being a mollusc means lacking bones and an internal skeleton, but snails are not unprotected.
Life on Earth offers a very wide diversity of habitats for snails. Surely you have found tiny snails under a stone, but you have also seen them on some stem or leaf of a plant. They are able to survive in natural environments or in places disturbed by humans, such as public parks and gardens.
The quantity and diversity is very large. Do accounts: only mollusks, the number of species is around 85,000 or even 150,000 and gastropods are about 80-85 percent of them. In the present, the world is home to more than 60,000 living species of gastropods.