You plant a row of lettuce in the evening and wake up to find nothing but stumps and silvery trails.
Snails and slugs are mollusks, related to clams and oysters rather than insects.
Irregular holes with smooth edges in leaves, flowers and soft fruit.
They feed at night and on cloudy, damp days.
No plant is completely snail-proof, but grouping vulnerable plants together makes protecting them easier.
Start with the least toxic and add more only if needed.
Seedlings: start them indoors and transplant when larger, or protect them under row covers or cut-off plastic bottles.
Step-by-step advice, charts and free garden calculators at Garden Voila.