What is a rabbits food source?

Rabbits are grazers, which means they nibble at grass and twigs and weeds on and off all day and night. Pet rabbits (domesticated European Rabbits) also like to graze -- that's why they should always have 100% 24/7 access to hay, so they can graze, and also so they can get the fibre they need to stay healthy (especially important for their teeth and digestion).

Another feeding habit of rabbits is that they love to raid gardens. Rabbits have a "sweet tooth," and because fruit and vegetables are high in sugars, rabbits will gorge on many garden plants. Pet rabbits have lost the instincts to know when enough is enough, so their human owners must strictly limit fruits and vegetables or else the rabbit will make itself very sick. Dark leafy greens, however -- like Romaine lettuce, spinach, basil, carrot tops, dandelion greens, mint, cilantro -- are low in sugars and rich in important nutrients, so it's very healthy for rabbits to eat some of these plants every day.

To make sure they're getting all the nutrients a wild rabbit in its natural environment gets, pet rabbits should also eat a high-quality dried pellet feed that's made especially for rabbits. These pellets can be provided in free form, so the rabbit can graze on them; but, most pet rabbits overeat their pellets, which is very unhealthy (and can make them sick) -- in that case, pellets must be limited.

See the related question below for more information about how to feed a pet rabbit.