A nutrient is a substance that provides essential nourishment for the growth and maintenance of living organisms. Nutrients are vital for various bodily functions, including energy production, immune system support, and tissue repair. They can be classified into two main categories: macronutrients, which include carbohydrates, proteins, and fats, and micronutrients, which consist of vitamins and minerals. Different foods contain varying amounts of nutrients, making a balanced diet important for overall health. For example, fruits and vegetables are rich in vitamins, while grains provide carbohydrates. Consuming a variety of foods helps ensure that the body receives all the necessary nutrients for optimal functioning.