Read more details on How to Read a Nutrition Label.
There are two sets of reference values for reporting nutrients in nutrition labeling:
1) Daily Reference Values (DRVs)
2) Reference Daily Intakes (RDIs).
These values assist consumers in interpreting information about the amount of a nutrient that is present in a food and in comparing nutritional values of food products. DRVs are established for adults and children four or more years of age, as are RDIs, with the exception of protein. DRVs are provided for total fat, saturated fat, cholesterol, total carbohydrate, dietary fiber, sodium, potassium, and protein. RDIs are provided for vitamins and minerals and for protein for children less than four years of age and for pregnant and lactating women. In order to limit consumer confusion, however, the label includes a single term (i.e., Daily Value (DV)), to designate both the DRVs and RDIs. Read more details on Percent Daily Value.
Physical activity increases calorie needs, so those who are more physically active need more total calories and have a larger limit for empty calories. People who are not physically active need less calories. See the chart of appropriate calorie amounts for different gender and age groups at How Many Calories Can I Have.