Naivedhya a Sanskrit word meaning 'offering to God' in the stricter sense of the words. It could be any offering, tangible or intangible. A resolution, a promise or even a willingness to do, perform or restrict from certain things can also be connoted as offering to God.
Naivedyam means, is food offered to a Hindu deity as part of a worship ritual, before eating it. As such, tasting during preparation or eating the food before offering it to God is forbidden. The food is placed before a deity and prayers are offered. Then the food is consumed as a holy offering. The offerings may include cooked food, sugarcane, and fruits. Vegetarian food is usually offered to the deity and later distributed to the devotees who are present in the temple. Non-Vegetarian is prohibited in most of the temples as of now, but there are evidences for non-vegetarian food as offerings to God. Offering to Goddess Kali include animals, such as goats or roosters,which are slaughtered in the temple precincts and offered. Many Hindus offer cooked food or some fruits to a picture or idol of a deity before they eat it.
God, prayers and wishes are more a belief and hence an offering to God is an extension of this belief. However, one needs to differentiate Naivedhya from 'Prasad'. Prasad is actually what one get from the God. The meaning of these words is usually attributed to food as we invariably offer to and receive from the house of Gods in the form of eatables.