Spiders mainly eat insects and drink water. Really big spiders may feast on small critters, like mice and birds.
Spiders are very opportunistic creatures, and they will eat nearly any sort of insect. Some spiders hunt the insects that they eat, while others may spin a web or wait in a burrow until a suitable meal walks by or flies in. Spiders drink water from natural sources.
Although nutritional requirements vary by species, spiders can usually go for extended periods of time without eating. In fact, some species may go for several months without a meal, while others may eat every day. Notably, some spiders inject their prey with enzymes that start the digestive process before the food is ever consumed.