Mike and I wrote it when we went on a diet two years ago. You can log in and add what you eat each day and use it to count your calories or keep track of what you eat. It already has about 40,000 foods on it from the .U.S.D.A database, or you can add your own foods and save them to use again. It keeps track of calories, fat, calories from fat, saturated fat, monounsaturated fat, polyunsaturated fat, protein, cholesterol, sodium, potassium, carbs, fiber, vitamin a, vitamin b6, vitamin b12, vitamin c, vitamin e, calcium, copper, folate, iron, magnesium, niacin, phosphorus, riboflavin, thiamin, and zinc. You can also log your weight everyday and see a graph of how you're doing with your weight. There's even a recipe calculator so that if you make something and you don't know how many calories, etc, you can input your indgredients, and it will calculate it for you.