The most common snail in gardens is, not surprisingly, called the garden snail (Helix aspersa) but it also known as the common snail in most books. Although not the most popular of creatures we all learn about them at junior school, how they carry their homes on their back and in winter how they seal over the entrance whilst they sleep soundly inside.
The garden snail is unpopular with gardeners for good reason, being very fond of low growing fruit and vegetables and the fleshy leaves of some varieties of flowrs such as hostas. Not a popular garden resident with keen horticulturists maybe but popular with song thrushes who adore them! The frequency of snails in a garden is not down to the abundance of food however. They need calcium to form their shells and so are more common in chalk and limestone soil areas. They also have problems crossing sandy soil so are rarely found in such environments.
They tend to be most active at night and spend the day behind flower pots and other sheltered places. It is apparently true that if you mark them and follow their movements that they will return to the same sheltered spot every morning after a night on the rampage amongst your plants.