The main way human beings obtain nutrients is by eating and drinking. Unlike plants, which synthesize nutrients from soil using sunlight to achieve photosynthesis, humans are not capable of synthesizing their own food.
Human beings are what is known as omnivores, in that they can obtain nutrients by eating either plants or animals. While some cultures, such as the Inuit, subsist primarily on animal foods, many others, such as several Asian Buddhist groups, are vegetarian, and try to avoid animal products.
The nutrients we need are divided into two groups, macronutrients such as carbohydrates, fats, fiber, proteins, and water, which we need in large quantities, and micronutrients, such as minerals and vitamins, which we need in only small or trace amounts.
Good health depends on having access to adequate amounts of both miconutrients and macronutrients, while not consuming them in excess.