In the modern world people are accustomed to hearing a great deal about nutrients and nutrition. Words such as protein, carbohydrate, vitamins, minerals, and fats are a regular part of daily life, yet few people who talk about these nutrients really know what they are. In fact, these are the basic building blocks of nutrition, whereby animal life is sustained. Whereas plants can get their energy directly from the Sun and the atmosphere, animals (including humans) depend on other organisms to provide them with nutrition. These other organisms include plants, which generate carbohydrates as a result of photosynthesis, as well as other animals that eat plants and thereby build proteins and fats. Plants also may contain proteins and fats, and both plants and animals contain vitamins and minerals. These nutrients, consumed in the proper forms and proportions, sustain life and prevent the miseries of malnutrition—a condition that can involve either under nourishment or over nourishment.